I had heard somewhere that Nikon techs would heat the screws up on the 50 f2 if they didn't come out, and they used a form of Loctite to set them in place. I'm restoring one I'm about halfway through it, I have to get the front off so I can re-grease the helicoids and clean the elements. What do I do about cleaning fungus? I got the outside of the elements cleaned and they look great. I also have a bit of spiderwebbing inside I think it's fungus too. The image created isn't bad and you can't notice any of these defects in the picture but I figured while I have it apart I may as well. I do plan on leaving it in the Florida sun wide open to kill off any fungus living inside it now. One other issue I'm having is the front retaining ring that says "Nikon" f=50mm Nikkor-H Auto 1:2 etc. I have the screw out but it won't budge. How do you get it out? Thanks in advance.