Feather Touch Focuser - PeterNagy
If the whole HSM assembly rotates while the motor is moving, it's likely the tiny set screw is loose right below the focuser. This set screw needs to be tightened so the focuser's collar does not rotate. The pinion assembly will need to be removed to get access to this set screw. Once the pinion assembly is removed, tighten the set screw and put back the pinion assembly.

If the whole HSM assembly rotates while the motor is moving, it's likely the tiny set screw is loose right below the focuser. This set screw needs to be tightened so the focuser's collar does not rotate. The pinion assembly will need to be removed to get access to this set screw. Once the pinion assembly is removed, tighten the set screw and put back the pinion assembly.