This knob is kind of complicated with quite a few internal parts. The position of the gear contact on the rack can be adjusted so that you use a fresher part of the gear, should the gear be worn. I've had a few apart but don't remember the layout. You don't need to shim the whole bracket off the focuser body, you can reposition the gear and shaft assembly within the knob unit. I've done it to make chewed up plastic gears work fine on fresh teeth. You'll have to take the knob apart and lay out the pieces in an exploded fashion, keep track, and use common horse sense to see how the gear can be repositioned if needed.
This will require removing the face plate off the knob, which is glued on, more like taped on as in a sticky back label. I've always managed to pry one off without tearing it up.
Edited by apfever, 19 February 2019 - 07:54 AM.