Yes, it's the mirror return mechanism that commonly squeaks. Anyway, thanks to a YouTube vid, it's fixed now. Sounds and operates like a new camera.
Originally Posted by benjiboy
As for the Canon EF, I'd love to own one someday - a very beautiful and well made camera. Still, the article you referenced does not state anywhere that it has a CPU. The EF does have an electronic auto exposure system with shutter priority, and it has an excellent Copal electronic shutter. Plus it has something that I wish all cameras of that era had: a voltage regulator circuit.