Skoal/Heco centering microscope stuck centering knob

[buffdan]

I have this Skoal centering microscope, which I used a few times in the past.
For some reason the adjustment wont turn now.
Like its super glued
The lens pivots when I push it by hand though.

I don't remember dropping it.. But.. who knows

I assume it might come apart if I gronk on it, but then will be left with parts
Any ideas?
Thanks, Dan

 

[matthewsx]

I’d try a little bit of heat, not even heat gun more like a hair dryer.

John