Frank Marshman posted:

Check the focus screen ground glass/ Fresnel lens by removing the viewing hood and pressing down evenly all around. If it drops down a tiny amount than the foam material that pushes it down needs to be replaced. Also if when you focus it at infinity the lens should be exactly there at the infinity mark and end of the focusing. If it goes past or doesn't quite get there the pressure foam is deteriorated. This is a very common problem with this camera due to the age of it. Much of the time it has been replaced by now.

Check the diaphragm activation by pushing the stop down button and see if the blades close completely and quickly at f22.

Finally you will want to waste a roll of film and check the back. Remove the lens, put the camera on B. Load the camera and crank it until it stops at #1. Holding the camera so you can see in it fire the camera on B but keep holding it. Take a pen and mark all around the film in the back through the opening so you can see where this exposure was made. Release the shutter and proceed to do this on every frame until you have completed the roll. You now can pull the film out, unroll it and see if the frames all look evenly spaced. Sometimes on a bad back or really dirty the frame marks will overlap and sometimes the spacing keeps getting larger until the last marked frame is off the end.

Lastly shoot a roll at different speeds to check the shutter.