It could be the pad of death. This pad is very old now, and it does deteriorate. In the latest version of the light seal instructions I explain a more simple way to replace the pad (you do not need to disassemble the camera if you will follow my instructions), and I provide a pad of the proper thickness and density cut to the right size for you...also the dust seal for the top cover. Good luck. When this camera is working properly it will take excellent pictures.
Jon