Hey all! I bought this lens a while ago but but didnt use it much and now I've realised there's some sort of light film on one of the back elements! Which causes this soft haze, emphasised by strong back light..

Anyway, I tried taking it apart but realised I couldn't get inside the actual glass lens elements, so I reassembled it (but did it wrong, that's another story!.. Focus doesn't quite hit infinity)

There's no way I could clean it myself is there? I've done a small amount of work on lenses before, I took apart my Canon EF 50mm f/1.4 and repaired that, but I couldn't unscrew the front bit of my 80 1.9, if that makes any sense to those of you who've done this before.

I inherited a couple of 1000s bodies from my uncle, which is why I bought the 80 1.9 and 55 2.8, but am on the verge of jumping ships to Pentax 67/105 2.4 cause I want to really start shooting MF and shooting it big, so

-Do you think it's worth sending it somewhere to have it cleaned?
-Should I try opening it up again myself?
-Any ideas how much I might get selling it in it's current condition?

I got it for $250 and its the N version, which I believe is a more highly sought after lens than the old one, I saw them for sale for around $500 keh etc! And my copy is in terrific condition, bar this odd hazy thing..