Ok, so I did a little more troubleshooting. Bear with me here...

I cut the config to just the following.

;Heaters

M308 S0 P"temp0" Y"thermistor" T100000 A"Bed"
M308 S1 P"1.temp0" Y"thermistor" T100000 A"Head0"
M308 S2 P"1.temp1" Y"thermistor" T100000 A"Head1"
M308 S3 P"1.temp2" Y"thermistor" T100000 A"Head2"
M308 S4 P"2.temp0" Y"thermistor" T100000 A"Head3"
M308 S5 P"2.temp1" Y"thermistor" T100000 A"Head4"
M308 S6 P"2.temp2" Y"thermistor" T100000 A"Head5"
M308 S7 P"3.temp0" Y"thermistor" T100000 A"Test"

M950 H0 C"0.out1" T0  ;Bed heater
M950 H1 C"1.out0" T1  ;Extruder0
M950 H2 C"1.out1" T2  ;Extruder1
M950 H3 C"1.out2" T3  ;Extruder2
;M950 H4 C"2.out0" T4  ;Extruder3
;M950 H5 C"2.out1" T5  ;Extruder4
;M950 H6 C"2.out2" T6  :Extruder5

creates no error, but when I un-comment out the last few lines....

;Heaters

M308 S0 P"temp0" Y"thermistor" T100000 A"Bed"
M308 S1 P"1.temp0" Y"thermistor" T100000 A"Head0"
M308 S2 P"1.temp1" Y"thermistor" T100000 A"Head1"
M308 S3 P"1.temp2" Y"thermistor" T100000 A"Head2"
M308 S4 P"2.temp0" Y"thermistor" T100000 A"Head3"
M308 S5 P"2.temp1" Y"thermistor" T100000 A"Head4"
M308 S6 P"2.temp2" Y"thermistor" T100000 A"Head5"
M308 S7 P"3.temp0" Y"thermistor" T100000 A"Test"

M950 H0 C"0.out1" T0  ;Bed heater
M950 H1 C"1.out0" T1  ;Extruder0
M950 H2 C"1.out1" T2  ;Extruder1
M950 H3 C"1.out2" T3  ;Extruder2
M950 H4 C"2.out0" T4  ;Extruder3
M950 H5 C"2.out1" T5  ;Extruder4
M950 H6 C"2.out2" T6  ;Extruder5

creates an error.

12/26/2019, 2:14:33 PM Warning: Sensor number 5 has not been defined
12/26/2019, 2:14:33 PM Error: M308: Pin 2.temp1 is not free
12/26/2019, 2:14:33 PM Error: M308: Pin 2.temp2 is not free
12/26/2019, 2:14:33 PM Warning: Sensor number 6 has not been defined

And every time I update the config I shut down the pi and cut all power for 20 seconds right now, just for grins.

How are you powering the servo? On my tool changer I have a separate 5v bus for things like the servos so that they don't overdraw from the duet 5v bus. My RPI4 sometimes indicates a low power situation with JUST it and the duet, no usb in the pi, no servos or other 5v draws from the duet 3 board.

@fractalengineer Whoops, thanks, that was dumb.

I am still getting occasional sequencing issues with my Duet3 and exp03 boards. The printer will not wait for the gantry to be in the right position to execute a tool change using the servo. The servo is on the main board and the core xy motors are on exp03 board 1.
This does not happen all the time, but often enough to mess up a print. DWC 3.1.1, RC11. I am wondering if this issue would go away if I put the core XY motors on the same board as the servo.

Thanks in advance!

Its working again. Consider it solved.
Thanks!

I am having issues upgrading my SBC Pi4 with a Duet3.

pi@duet3:~ $ sudo apt-get update
Hit:1 http://raspbian.raspberrypi.org/raspbian buster InRelease
Hit:2 http://archive.raspberrypi.org/debian buster InRelease
Err:3 https://pkg.duet3d.com unstable InRelease
  Temporary failure resolving 'pkg.duet3d.com'
Err:4 https://pkg.duet3d.com stable InRelease
  Temporary failure resolving 'pkg.duet3d.com'
Reading package lists... Done
W: Failed to fetch https://pkg.duet3d.com/dists/unstable/InRelease  Temporary failure resolving 'pkg.duet3d.com'
W: Failed to fetch https://pkg.duet3d.com/dists/stable/InRelease  Temporary failure resolving 'pkg.duet3d.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.
pi@duet3:~ $

I don't know if it is a DNS issue on my end or if something is down.

Thanks!

What size bearing does it use?

Just did the latest FW update, it went flawlessly.

Hmm, Ok. I will try that as soon as the printer is done printing and I have a wee bit of down time. Thanks!

@Danal

Nope, I made this video tho show what I am doing.

https://youtu.be/Fn2VejqtvBY

Hmm, thanks for the info. I am 99.99% sure that right now if I where to upload a new firmware file for the Duet3 or an expansion board I would have to re-flash the firmware using Bossa.

Here is my setup.