Diopter jammed, need suggestions please

[Crater Eddie]

My "new to me" LOMO MFN-11 trinocular head looks pretty good, except the diopter adjustment is stuck. It won't turn a bit either direction, and of course it's out too far for comfortable use. Has anyone had to deal with this? Any and all suggestions are welcome.
CE

[microgreen]

Hi CE

It could be solidified Russian tank grease or is there a dioptre locking screw?
It does look like the lens tube could be taken off by removing the base fixing screws.
I don't think that removal of the prism covers would give you access to the dioptre adjustment mechanism.
I'm sure you will have investigated these suggestions
Not much help I'm afraid
Good luck
Tony
East Riding of Yorkshire(UK)

[Crater Eddie]

Tony, I hadn't thought about the possibility of a locking screw. I didn't notice one, but I sure will look tonight to make sure!
Otherwise, you might be right about the tank grease. I'll see if gently warming the area will free it up.
Thanks for the suggestions.
CE

[Crater Eddie]

UPDATE:

It was that crazy Russian tank grease! I'm sure it was great for tank tracks, but they sure should have found something a ittle more stable for microscope parts. Gentle warming with the hair dryer freed it up enough to turn quite well. It won't unscrew all the way, at least not yet, but I am able to turn it what feels like all the way in both directions. It comes to a definite stop before it unscrews all the way, so maybe there is a "stop" there somewhere. I am satisfied with being able to adjust it for now, but would like eventually to be able to take it apart and clean it and replace the grease.
Thanks to Tony and Gekko for both coming up with the solution.
Also, the ocular tube is a little loose at the base, this is what was putting it out of collimation. I can fiddle with it and bring it into alignment, will have to figure out how to tighten that up at some point.
CE

[75RR]

Gentle warming with the hair dryer freed it up enough to turn quite well.

Good news.

Found this link which has several links within it. There are a couple about maintenance and lubricants among others.
I expect you probably have them ... this is just in case you missed one or two.
http://www.microscopy-uk.org.uk/mag/ind ... -Lomo.html

[Crater Eddie]

Yes, I have read these already but thanks for posting the link. It's always good to have good links handy.
CE