To the OP?
It seems to me that your pointing errors on slewing are mechanical.?
Is the scope balanced in RA and DEC?
Have you tried slowing down the GoTo speed to see if things improve???
Mechanical slippage can easily occur at the couplers between the gear box and the worm. I've had that happen and it's frustrating as heck.??
Please check those 4 small set screws on each. The worm shafts have a flat but the gear box shaft does not.?
If it slips under the torque of slew starts it would give you exactly the problem you describe.?
Michael?
