Need help with lose stage translation control

[nobody]

Hello and happy New Year!

I need help with loose/wiggling stage control stick (see video below). It moves a bit in all directions and knobs drift the stage in both axis at the same time. They also seem a bit stiff (much more force is needed in comparison to turning the fine-focus knob). If I hold one and turn the other one, it works as intended.

It’s a used microscope and I received it in a great condition, apart from this issue. It came in an aluminum travel case, but instead of velcro harnesses, it was bubble-wrapped inside. Hence, there was probably some travel and my assumption is that the stick received too much stress during the transport.

Any ideas how to fix this? Does anyone have a service instruction manual to similar stage?

Many thanks!

Video (4MB):
https://www.dropbox.com/s/pojmpehg2p9rw ... 1.mp4?dl=0

[MichaelG.]

I am not familiar with that model of ‘scope: But I am pretty sure that the ‘control stick’ should not wiggle !

It may be that the tube is threaded, and just needs tightening
… or it may have a flange with fixing screws.

MichaelG.

[Scarodactyl]

I'm on mobile and can't watch the vid, so just a couple general notes. This happens with stage controls. Sometimes the rack has been pushed out of position, leaving the gear loose.
Int his case sometimes the bolts holding the rack can be loosened and allow you to push it flush with the gears before retightening. It takes a bit of tweaking to get the tightness right.
As to the stalk it's usually an outer threaded shell holding one knob and an inner threaded rod holding the other. The knobs are locked on with a set screw. You can usually take it apart pretty easily and adjust it.
Generally, these tend to be intuitive to work on, they just take a little time and care.

[nobody]

Thank you gentlemen, good tips. I already tried to re-adjust the geared plate (y axis) but it didn’t help. There is one screw inside the handle accessible from the bottom I can’t reach. I will get a proper tool to try that out, it seems like something Scarodactyl mentioned.

Thanks again for taking the time to reply!

(the model is Motic BA310)

[Dubious]

I recently acquired the Motic BA300, which looks to have the same or very similar X-Y positioning mechanism. If so, the control rod definitely should not wriggle that way. It could be something just needs tightening, or something could be cracked/broken. Also, of course, the X and Y controls should operate independently of each other. Is that ~1x2" toothed plate with the 3 screws firmly in place? Can you do the video again, this time from the underside, showing where the control rod enters the stage? (If you remove the power cord, you can lay the microscope gently on its back for the video.) That might provide some clues.

[nobody]

A small update: Thanks to your suggestions, I was able to fix the wiggle. Even tough, I did it before reading Dubious' comment, he was spot on. The loose pole problem was because of the geared plate (see the image). It must have received some damage during travel as I even needed to stick a piece of wood inside the gap to make the ride more consistent. However, it's perfectly usable now.

The minor problem that remains is that no matter how I try to set the tension counter-screws on the knobs, they are still on a stiff side (similar to coarse focus knob) and often create movement in both axis. I will try to clean it up with WD-40 and apply some lubricant. Do you have a recommendations on that?

Side thought: Perhaps I am just asking too much from a second hand inexpensive microscope when trying to achieve the same silky smooth knobs I remember from 25 years ago on a beautiful Leitz scopes we had back in the high school.

[Dubious]

Glad you were able to fix the wriggle. Were you able to fix the interaction between the X-Y controls? Moving one should not affect the other--sounds like something needs cleaning and reoiling.