Are you using it professioanlly or as a hobbest?
Replcae the seal, use it to death n enjoy the hell out of it. It's a good deal regardless of fungi n all that nonsence. That is a great camera and you wil find out why soon enough. That soft focus lens is a PIA to focuse since it has to be done at ƒ8 in order to see sharpness. The preview is a sticky type so you can leave it in the preview mode untill you are readu top shot then flip it over n set your stop to ƒ4 for max glow or stop down one to reduce the glow a bit.
The other discs allow you to use it at other stop downs without actually stopping down the iris.. but you loose some of hte glow that way as well.
Get a 90mm ofr general use, a 180 for portraits and the 50 is an amzing lens every RB owner should have to say his kit is complete.. it is awsome.