Quote Originally Posted by lambertsz
Hi Bjorke,
I did remove the focus gearcap and gear but still unscrewing isn't possible.
It indeed may have been oxidized but I even fear that the previous owner might have used strong glue! ;-)
I have a C3 with a telephoto lens that I use now and then. Once the cap and gear are removed, the lens is turned Counter-clockwise to remove it. It may be cross threaded or glued in. If that is the case, it will be difficult to remove without doing damage. Sometimes just hot water will loosen glue.

A spray of WD-40 penetrating oil on a Q-tip, then wiped along the base of the lens may help loosen it.

I hope this helps.