Hi everyone! I recently came across a nice Pentax ME Super body in and exchanged it for one of my Zenits at the local camera fair. It is in great condition with light seals recently replaced and i wanted to get into the PK system for lightness and to check out the lenses. I ordered a 1.7/50 and a Sigma mini-wide to go with it. However, i must have done some damage to it when cleaning it because it now greatly underexposes. Let me explain: While i was waiting for the lenses to arrive i noticed some sticky foam material between the mirror and the focusing screen where a band of fabric is. As it was clearly ready to peel off i gently removed it. Today the Sigma arrived and after fitting it to the camera i noticed serious underexposing (2.8 directly into the sun, the camera chose a slow 1/250 with ASA set to 400) which persisted after removing the lens. Removing this thin foam stripe must have moved some of the sticky goo onto the light sensors or there must be some light leak into the mirrorbox causing the camera to underexpose. Any help would be great. I'll upload a picture of the mirrorbox as it is now so you can have an idea.