I've mentioned it in description of the problem that there was no external mechanical force on the mount - it stopped at homing limit as was set in APCC.
The mount was well balanced in both Ra and Dec.
There was no payload, no telescope mounted on top, just scope rings with losmandy plate and a smallest CW just to balance everything (when freeing the Ra/Dec locks each axis was almost perfectly balanced).
This was done for testing purposes alone.
I still wonder why motor stall events were triggered at a moment when mount was parked in place when hitting homing limit (and I repeat - it didn't hit anything physically at that moment).