Topics created by AlexZ.

Is there a size requirement that makes you want to use 4 motors instead of just 3?

I assume you have a driver for X Y and extruder, leaving only 3 for Z. Perhaps it would make sense to add a toolboard for the extruder, freeing up a driver for the 4th Z.

If you really want to stick with two motors on a single driver, see here for wiring them in series to a single driver.

https://docs.duet3d.com/en/User_manual/Connecting_hardware/Motors_connecting#duet-3

@AlexZ, it is unlikely to be the mosfet. Generally when they fail they do so permanently.
Is the new heater a high wattage heater (more than 40W)? Is your heat block a copper block rather than aluminum? In both cases I have found that standard PiD tuning is less than ideal and needs hand tweaking.
Also, the actual temperature graph may tell you more about what is happening.

@Cognirit we've also integrated the scanning Z probe into our new Revo Roto Tool Board.

I suggest using a 3- or 4-wire heatsink fan. The heatsink fan is normally run at full power, so a 3-wire fan would suffice. Then you can check in damon.g that if the hot end is above a certain temperature, the fan RPM reading is high enough.