It all starts with some wonky shutter function...but not "wonky" in a good way.
Sometimes it works fine, sometimes it only exposes half the frame, sometimes nothing at all. Over time, your early model EOS camera stops taking photos all together.
You are the unfortunate victim of some poor engineering (or some say planned obsolescence) from Canon. It is a common failure mode for early EOS cameras caused by a foam shutter bumper (some say a foam light seal) that has deteriorated over time and turned into a sticky black goo. That goo gets all over your shutter and causes some funky shutter behavior in the beginning and a total malfunction over time. For those of you who work with old cameras, deteriorated tar like foam seals are a common sight. Usually, you scrape it off and apply new foam and move on with your life. Here it is a little trickier!
I call it, "The Sticky Shutter Syndrome."
In this instructable, we will attempt to reclaim your Canon from paperweight mode and get back into picture taking mode!