SOURCE: ETX-90 Focus
I suggest trying a different eyepiece first to see if that's the problem. Otherwise, if it was moved without adequate protection, there is a chance the mirror was shifted or damaged. A damaged mirror can't really be fixed since it's specs are very rigid. If it turns out to be a problem with the mirror the best thing to do is find an expert on telescope mirrors to try and fix the problem.
SOURCE: focuser broken
Not really a solution, but anything is better than a posting that get's NO response. It sounds like the rack and pinion drive has collapsed. If you're good with your hands and have a knack for things mechanical maybe you can dissassemble the stage mounting and see how it's meant to work. If something has come loose rather than broken maybe you can fix it. If teeth have stripped from the drive gear - you may be unable to effect a repair. I guess trying to fix it is better than doing nothing. Have a good 2008
kevin
SOURCE: Microscopes
Well then ?
It sounds like you do have a pre-tension problem, and if the fine focus is slowly turning as the stage desends, that is where your problem is. If you could tell me make and model, fixing it should be no problem.
Regards.....Dave
SOURCE: Focus knob screw
I've had the same problem. Unfortunately, these are knock-off scopes. If the shaft that the focusing knobs attach to is still there, you can replace the knobs themselves by ordering THIS part. If the shaft AND the knobs are both missing, you'll have to replace the entire focusing mechanism (sorry, but I don't know where to order the housing from). Hope it's more helpful than the prior answer.
SOURCE: focus knob turns but nothing moves
The Celestron manual for this scope has nothing to say, but on the underside of the focuser assembly, between the 2 focus knobs, you may see 2 screws.
They might be thumbscrews or some other screwhead type. One is the adjustment for the focuser internal clearance, or looseness, and the other is a focus travel lock.
If present, try backing both off 1/2 turn from tightness, and then experiment to see which is which. The focus lock will have no effect until tight, when the focuser will cease moving, as is now. The other screw will gradually remove looseness and rattle from the focuser until it just moves smoothly, with no back and forth loose feeling at the knob.
If neither of these screws is visible you will have to take it to a binocular and telescope shop, where they should not charge much.
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