Recently I had a difficult night in terms of focus stability and so I'm taking a closer look at the focuser performance on my AT90EDT. I've noticed two issues: first, I've got some backlash due to wiggle in the pinion housing. I've linked a short video demonstrating the problem. It's really easy to see: https://www.youtube....?v=iqNhrgIzcFM I've tried cranking down the four screws on the bottom of the pinion housing but that binds the entire shaft.
The other issue is with the fine-tune focuser knob. It barely works at all and I have the grub screw cranked in as hard as I dare. It will spin all day long but neither the tube or the course-focus knob move at all. I've seen the instructions here: https://www.cloudyni...74259440284.jpg but you can see from the video that I don't have a '#2' screw so I don't know where to go next.