Owner of EOS Film Cameras up to the EOS 50/E models may get a sticky line up the left hand sie of the shutter curtain this can slow down the shutter speeds or in worst case render the camera inoperative. This is caused by a sponge damper at the bottom left hand inside of the shutter run( just below the film gate) and over time deteriorates which rubs an oily line on the left hand side. Most people will discard their cameras due to this or use lighter fuel which leaves a stain on the shutter. Dont use lighter fuel I found the best way is methylated spirits on cotton bud this can be wiped over the curtain gently it dries fast leaving no stains or it does not affect the coating you may have to repeat the operation until its completely gone leave the shutter to dry in between cleaning and test fire the camera you will find eventually no more goo appears the camera will now work with correct shutter speeds. I have just done this to a £5 EOS 100 which was otherwise in mint condition the shutter was working fine but I cleaned the whole of the shutter blades to be on the safe side. This also works on those sticky grips and back doors where they coated a rubber finish this is actually a glue based coating and works immediately it does not damage the plastic and you will find that the grip has a leather finish moulded surface underneath the rubber coating.
