I just finished a test print with 100% success. Thanks for the suggestions.
I think the major problem was that I never removed the gap from when I was printing both the model and support with pla. I had completely forgotten about this.
I also printed slower although I don't actually know which of the many speeds is used - I suspect it was 26 mm/sec for petg and pla at 40 mm/sec.
The petg and pla stuck together to a limited degree ... enough to hold everything together yet not so much as to make support removal difficult.

I only have two words ...... Woooooo Hoooooo !

I think I would like to give some cudos to all the people bending over backwards to help abstracktlighting. You are showing an amazing amount of patience !

It is highly unlikely that the SSR has failed since it is not stuck in the 'on' position. It is way more likely that there is a wiring error.
Are you aware that the positive line will always be high no matter if the heater is on or off?
Simply wiring the negative to ground will cause all these issues.
Verify the ruting of the two control lines.

I would like to add my 3 cents (good grief, It turned into a $30 'Mobby Dick' novel). It's been said before - the support from both Duet and the community is incredible. There have been many occasions where I was impressed about the amount of patience and knowledge that is shown every day.
Having said that, there are only so many things that can be done when one is sitting in front of a computer, totally removed from the actual device that is causing issues. Things that might be immediately obvious sitting in front of the Duet may take days and days to sort out remotely.
I have had my fair share of "operator problems", Some I have had sorted by people here, some I have fixed myself after bouncing the issue off people here and they got me thinking the right direction and then there were too many issues that just took hours or even days of screwing around before the light went on.
I have learned an incredible amount by pounding my head against the wall and sticking with a problem and reasoning things out. You probably don't want to hear that but immersion into the whole 3D printer scene is pretty mandatory if you are going the "self built" Duet route. It is not a product that is turnkey - it is a small part of a large and complex machine. A machine that Duet has no control over.
It is not fair to purchase a car engine and expect the manufacturer to be able to figure out why the car that you built around the engine tops out at 50 km/hr for some reason.
In addition to all that, the Duet 3 and RRF3 is a new product that is still being developed as I type this and changes to the software happen on a regular basis. It is not a 'stable' product as the Duet 2 series is. There is a steep learning curve to go from RRF2 to RRF3. I still work with a Duet2 but have migrated to RRF3 which was a big step for me. A step that isn't for everybody at this stage.

I can only suggest to stick with it and eventually it will 'click'. This applies to the Duet to some extent but I would say that it is less a Duet issue and more of an issue of the whole 3D scene.

I don't recall what your particular issues are. Maybe you are doing something that has never been done before, maybe you are doing something that is a real challenge even for a person that has been involved in 3D printers for many years. You can't expect things to just magically work. Thankfully, the community around the Duet shows incredible patience and sometime I must admit, more patience than I would ever be able to muster.

Sometimes it helps to approach a problem from a different perspective. Start a new thread along the new direction and maybe we can help you that way and eventually get to your current problem via a back pathway.

I find that sometimes it is necessary to take a break for a couple of days. More often than not, this will clear up my thinking and new avenues will open up.

Last but not least, you can't expect to purchase all the bits and pieces for a printer and expect to have a working unit in a given time frame. It requires time to develop a new product and when you build a new printer that is exactly what you are doing.
Sometimes, when you NEED a printer in a month, it might be best to buy a commercial product with full support and satisfy your desire to build a printer when you don't have the pressures of needing it in a month or 6 .....

And if you find that the 'pull test' is not passed then double up the BARE wire at the larger connector of the Duet. Solder on the wiring is bad juju!

I can also highly recommend crimpers from 'Engineer'. They make excellent crimps IF you take care (I guess that applies to all crimpers, never mind). On the other hand, a connector pin has a specification in regard to the wire it takes. If you put a 24 ga wire in a pin that requires a 20 ga wire, your success rate will take an enormous dive. To get around that, strip twice the length of wire you need and double it up. You MUST remove the insulation from the overlap. You can't just bend the stripped wire back over the insulation and crimp that.

With about 90% certainty, I can say you have a dud thermistor. Another 5% goes to a bad connection someplace and the last 5% is phase of the moon related. Notice there is 0% chance of this being tuning related.
Why am I so certain? Because I happen to have had the exact same issue and struggled with it for quite some time before deciding to put a second thermistor on the build plate. I relegated the original thermistor that is buried in the heater to backup status and use the new thermistor as the thermistor 'in charge'.
I display both values in the temperature chart for kicks and the original one is still doing it's dance.
As a side benefit, the replacement is more accurate as it isn't buried in the heater.
A tuning related issue will show an undulating temperature but what you see here is sudden temperature spikes, instantaneous changes in temperature, that are not physically possible.
You might be able to tune it a bit, as you found out, to stop the safeties from kicking in or you might change the safety mechanism to be less sensitive. This can buy you some time to get a new thermistor in.

I think you guys all swallowed some happy pills ....
While I like my Duet 2 very much, I have run across many things it can't do (yet). Some things are exotic but other things not so much (like being able to do basic decision logic in a macro).
Apparently logic is one of the new things in the new version of the software and I am looking forward to the day when I upgrade but the point is that it is not the ultimate do everything setup. It can't be, there is no such thing.

My intent was not to discourage you but to give you some things to think about. I do agree though that speed could probably be dealt with manually until you are ready to dive a bit deeper. The concept of turning the VFD on and off under duet control is very easily implemented and can be done in little steps by first implementing the control manually with a remote (to the VFD) switch and then replacing the switch with a relay.
Depending on what you are running with the VFD, speed control might not be that critical anyhow. If, for example, you are running a router spindle, you should be able to do the vast majority of cuts with a single set speed.

Further thought: I noticed these inputs .., SPH,SPM,SPL. I am thinking that these could be for 'speed high','speed medium' and 'speed low'. If that is in fact true then you might not even need direct speed control. They could be pre-settable speeds and you could then implement 3 different speeds with just relay control. It might even turn out that those lines are a binary input in which case it could be 7 preset speeds. Something to explore if you don't need true variable speed!

Could the pin be sticking? I run into that but only rarely.
If you power cycle the printer, does the pin drop without manually pulling it down first ?
I am afraid that this is as far as my experience goes. I do know that sometimes a sticky pin has to be removed and cleaned and sometimes it needs adjusting with the little screw on the top but I am not the right person to advise on either of those procedures.

As has been said - same wattage, same speed.
The choice of supply voltage should really not be made based on the heaters but rather based on the whole system. One of the reasons I went to 24V was because the current to the heaters drops when going to 24V and I had issues with connectors/connections heating up beyond safe levels in a 12V system. Going to 24V dropped current in half and took care of that issue.
24V will also give your stepper motors more pep and allow higher speeds if this is an issue for you.
Generally speaking, 24V is considered 'better' for the class of printers that are equipped with Duets. 12V is more suitable for low cost printers.

Second question: answer is "no"

I don't know if this is related to your problem but your temperature graphs show substantial variance and that might cause a shutdown.
Have you run tuning on heaters one and two?
Does the shut-down coincide with the start of a cooling fan ?

mmmmmmm .... acetone smell .... I LOVE modern chemistry and all the wonders it can supply Goes together nicely with any kind of hot filament smell!
Peanut butter is better used for rat traps around here. The buggers just can't resist it

O M G !!!!

I use a food dehydrator that controls the temperature. I also have an older one but it doesn't control temperature so I don't use it for drying filament.
Having said all that I find that moist filament is rare for PLA and PETG. I leave the spools on the machine when I am not printing. At least on PLA there is a situation where the filament gets extremely fragile in the section from the spool to the extruder so it's got to be treated careful or reloading is required. There is no difference in material once it's been melted. IMHO this phenomena is caused by exposure to air after getting micro fractures from un-spooling. I takes about a week of sitting before going fragile.

Have you checked that all runs of your wires have BOTH POWER AND GROUND only connected to their respective power and ground connections?
Sounds to me like you might have decided to inter-connect ground someplace since "it's only ground"

Exactly .... no difference in actual printing, only in homing.
Again "trick question and not fair"
The original question was fair though .....

@mrehorstdmd said in Game time: Spot the difference:

You'll never get this (one unless you've been reading other threads...)

No fair, trick question as there is no printing difference.

My vote is for reduced flow resulting in under extrusion