What usually happens is that the frameline dial does not engage the lever which switdhes the framelines. Usually you can fix this quickly by removing the top cover and moving the switch so the 50mm frameline shows, then set the dial on the top cover, and carefully reinstall the top cover.
The only tricky part is removing the shutter speed dial before removing the top cover, you can do this more easily by setting the film speed to 400, and then setting the shutter speed to 1/15. This will allow the three set screws to line up. Back out the screws (don't remove them, they are tiny, and a little difficult to put back into place), then lift off the dial. The aperture value in the meter should show the orange f/2.8 setting. Then remove the set screws around the shutter button collar, the wind and rewind levers, and the screws holding on the top cover.
I love the Canon 7 cameras, and I also have a black one mounted with the big 50/.05, its alot of fun to shoot.