Not too long ago I remember coming across a web site which discussed the 'resuscitation' of selenium cells. Long story short, the chap basically stated that 'all' selenium cells are repairable with a little bit of work. I'll try to see if I can find the link.
As for the FED 5C itself...I have a 5V and although the fit and finish is deplorable, and the materials painfully cheap, it is a very reliable camera which has always done what I asked it to do. The only thing which really bugs me is the viewfinder; its awfully squinty. I much prefer my Zorki 4, but the Zorki is a lot 'fussier' even if it's sexier looking and has a better VF/RF.
Kent