Originally Posted by Huss
Well the light leak is from a missing seal above the sprocket gear. It seems when they took the kamera apart to paint it they mis-placed it.
Something internal, ouch. I was going to say, I fixed the light leaks in my Zorki by taping all around the back door. Different camera architecture entirely though, but it helped that it was something simple. Hopefully you can get yours sorted out.
Nikon S2, S3, F, F2, F3, FM2, FA, N90S, D80, D7000, D750, Sony a6000, Canon IIf, Leica CL, Tower type 3, Zorki 4, Vito B, Perkeo II, Rollei 35....