Nikon E200 focussing failure

[RCAguy]

Suddenly the focus is rough, ratcheting, and unable to drop its full range. I've taken it down to the slider visible with its tracks on either side, but hesitate to go further until help arrives - thanks. - Robin

[aidanmoore]

I took the back off a E200 to see how the stage attaches. Perhaps the screws that hold the focus assembly has loosened from the stage rack and pinion assembly

[RCAguy]

All screws were tight - it’s inside the focussing mechanism housing. Can anyone guide me to get inside? Or a source for parts if not the whole mechanism? Thanks.