I think I ended up narrowing down the issue. My apologies as it seems to have been setting related (I was driving my new NEMA23 way too fast according to the reprap firmware EMF calculator), I backed off the maximum speed and my problem seems to have resolved itself. Thank you all for your suggestions and help.

Well confirmed, heater cartridge needed to be replaced. Thanks for the help.

Well confirmed, heater cartridge needed to be replaced. Thanks for the help.

@phaedrux nope, will try replacing the heater tomorrow and see if that solves it

@phaedrux Yes the hotend heater screw terminals.

I'm not actually sitting at it right this second but earlier I actually measured between E0- and GND, which showed ~24V when off, ~0V when the heater is on. So the FET seems to be working fine. Some kind of configuration error then maybe? I guess potentially the heater cartridge could be toast.

I'm having a problem with my Duet 2 WiFi, it was working though I was getting intermittent heater faults on the hotend. I thought that maybe this was due to a flaky connection (I had leads soldered right to the board because the screw terminal had fallen off) so I ended up replacing the screw terminals. Now I see 20 degrees on the dashboard, but when I turn the heater on (LED comes on), I don't see a change in temperature.

I unplugged the thermistor and saw -273.1, measured the resistance of the thermistor at 125 kOhm, saw the resistance decreasing when I held onto the hotend.

My config is attached below:
; Configuration file for Duet WiFi (firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Mon May 02 2022 10:44:06 GMT-0500 (Central Daylight Saving Time)

; General preferences
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"Cantilever Monster" ; set printer name

; Network
M552 S1 ; enable network
M586 P0 S1 ; enable HTTP
M586 P1 S0 ; disable FTP
M586 P2 S0 ; disable Telnet

; Drives
M569 P0 S0 ; physical drive 0 goes forwards X
M569 P3 S1 ; physical drive 3 goes forwards Y
M569 P2 S0 ; physical drive 2 goes forwards Z
M569 P4 S1 ; physical drive 4 goes forwards E
M569 P1 R-1
M584 X0 Y3 Z2 E4 ; set drive mapping
M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
M92 X76.196 Y99.52 Z806.086 E420.00 ; set steps per mm
M566 X1200.00 Y1200.00 Z400.00 E3000.00 ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z20000 E1200.00 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z250.00 E250.00 ; set accelerations (mm/s^2)
M906 X1200 Y1200 Z1200 E800 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 S1 ; set axis minima
M208 X212 Y300 Z326 S0 ; set axis maxima

; Endstops
M574 X1 S3 ; configure sensorless endstop for low end on X
M574 Y1 S3 ; configure sensorless endstop for low end on Y
M574 Z1 S1 P"zstop" ; configure switch-type (e.g. microswitch) endstop for low end on Z via pin zstop
M915 X Y R0 F0

; Z-Probe
M558 P0 H5 F120 T6000 ; disable Z probe but set dive height, probe speed and travel speed
M557 X15:215 Y15:195 S20 ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B3950 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B1 S1.00 ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0 ; map heated bed to heater 0
M143 H0 S120 ; set temperature limit for heater 0 to 120C

M308 S1 P"e0temp" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin e1temp
M950 H1 C"e1heat" T1 ; create nozzle heater output on e1heat and map it to sensor 1
M307 H1 B1 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S280 ; set temperature limit for heater 1 to 280C

; Fans
M950 F0 C"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1 ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency
M106 P1 S1 H1 T45 ; set fan 1 value. Thermostatic control is turned on

; Tools
M563 P0 D0 H1 F0 ; define tool 0
G10 P0 X0 Y0 Z0 ; set tool 0 axis offsets
G10 P0 R0 S0 ; set initial tool 0 active and standby temperatures to 0C
M572 D0 S0.5

M501
M570 S120
; Custom settings are not defined

I think I ended up narrowing down the issue. My apologies as it seems to have been setting related (I was driving my new NEMA23 way too fast according to the reprap firmware EMF calculator), I backed off the maximum speed and my problem seems to have resolved itself. Thank you all for your suggestions and help.

@dc42 so just tried it, and it doesn’t seem to have alleviated the issue

@dukemachine my apologies life got a little busy. Will try it today.

@phaedrux I’ll give it a shot tomorrow and report back. Thanks!

Well for anyone looking at this one I have a temporary fix anyhow:

I disabled arcs in my post processor (no G2/G3 commands) and my output is as expected.

@mjlew Thanks for taking a look!

Well M115 reported the following:
FIRMWARE_NAME: RepRapFirmware for Duet 3 MB6HC FIRMWARE_VERSION: 3.3 ELECTRONICS: Duet 3 MB6HC v1.01 or later FIRMWARE_DATE: 2021-06-15 21:45:56

The other G2 commands seem to be behaving fine. I originally suspected it might be a mechanical issue, but this is the second cut its happened in, and it doesn't happen in the same spot on the X axis, and its suspiciously consistent (i.e. in the cut, it occurs at the same point, but not the same point between cuts). Belts are tight, pulley set screws are tight, its not binding so