In case people have not heard, focusers fitted with High Res Stepper Motors now have a clutch that enables them to be operated with the manual focus knob.
Even when fully tightened there is enough slip in the clutch to stop the motor stalling when it reaches a travel limit.
Ron quoted me $US50 to upgrade mine, but needs it returned to the US to do it. The freight would be more than the upgrade.
See about half way down
this page.