Had a more precise look to the logs, and immediately notice an unexplained variation of the DEC axis position as reported by the motor controller firmware. For instance during the calibration:

[2020-09-23T23:25:15.234 CEST DEBG ];EQMod Mount : "[SCOPE] Current encoders RA=8153754 DE=9502321 "
[2020-09-23T23:25:15.885 CEST DEBG ];EQMod Mount : "[DEBUG] Timed guide North 1250 ms at rate 7.52053  "
[2020-09-23T23:25:15.887 CEST DEBG ];EQMod Mount : "[DEBUG] SetDERate() : rate = 0.5 "
[2020-09-23T23:25:15.887 CEST DEBG ];EQMod Mount : "[MOUNT] SetMotion() : Axis = 2 -- dir=forward mode=slew speedmode=lowspeed "
[2020-09-23T23:25:15.900 CEST DEBG ];EQMod Mount : "[MOUNT] SetSpeed() : Axis = 2 -- period=1329692 "
[2020-09-23T23:25:17.181 CEST DEBG ];EQMod Mount : "[DEBUG] End Timed guide North/South "
[2020-09-23T23:25:17.290 CEST DEBG ];EQMod Mount : "[SCOPE] Current encoders RA=8153804 DE=9502334 "
[2020-09-23T23:25:18.478 CEST DEBG ];EQMod Mount : "[SCOPE] Current encoders RA=8153832 DE=9502332 "
[2020-09-23T23:25:19.455 CEST DEBG ];EQMod Mount : "[SCOPE] Current encoders RA=8153856 DE=9502342 "
[2020-09-23T23:25:19.601 CEST DEBG ];EQMod Mount : "[DEBUG] Timed guide North 1250 ms at rate 7.52053  "
[2020-09-23T23:25:19.604 CEST DEBG ];EQMod Mount : "[DEBUG] SetDERate() : rate = 0.5 "
[2020-09-23T23:25:19.605 CEST DEBG ];EQMod Mount : "[MOUNT] SetMotion() : Axis = 2 -- dir=forward mode=slew speedmode=lowspeed "
[2020-09-23T23:25:19.611 CEST DEBG ];EQMod Mount : "[MOUNT] SetSpeed() : Axis = 2 -- period=1329692 "
[2020-09-23T23:25:20.890 CEST DEBG ];EQMod Mount : "[DEBUG] End Timed guide North/South "
[2020-09-23T23:25:21.533 CEST DEBG ];EQMod Mount : "[SCOPE] Current encoders RA=8153907 DE=9502344 "
[2020-09-23T23:25:22.602 CEST DEBG ];EQMod Mount : "[SCOPE] Current encoders RA=8153934 DE=9502343 "
At the end at the first Timed guide pulse, the DEC axis changes by itself: 9502334, 9502332 then 9502342. Starting from 9502321, the first guide pulse is correct leading to 9502334 (~12-14 steps), then it moves by itself, and the second guide pulse is only 2 steps from 9502342 to 9502344. But 9502344 is almost correct starting from the beginning. Unless another application is moving the mount, I have no explanation. I did not go further, if I understood South guiding works correctly as you reported, I don't know why the firmware makes special corrections on the North axis. I don't own a STM32 dev board to debug the firmware and I suppose their ASCOM driver is closed source. Did you try with the ASCOM eqmod driver ?
It seems they did not solve the issue (or consider this is not a normal usage of the mount) (thanks @Gonzothegreat) What do they mean with 'telescope pointing forwards' ?
An explanation of the existence of these 2 motor firmwares (altaz and eq) may be that the handcontroller is altaz only and always send commands to the motor board as if it was in altaz mode. If the mount is on an eq wedge you then have to change the Dec axis speeds in the motor firmware and that may explain this issue. But not sure.

Read More...