In terms of the fixing of the triangle light leak, the first thing I did was to cut a small piece of black paper out with a
perfectly cut hole in it and I glued that to the metal shutter assembly, on the lens side.
Then I put a small piece of black paper tape on the metal disk with the hole in it (the shutter itself, I guess). I
placed this at the corner of the "window" in the spinning shutter that faces up at the start of its cycle. That's where most of the light seemed to be coming from, both at the start of its cycle and after the
shutter lever was released.
I found that if I held my eye right up to the camera, at the lens, both front and back,I could see, on the close cycle of the shutter, there was a triangle of light just getting
through. I used that as a point of departure for putting the paper and the paper tape on.
The key was, putting my eye right up against the shutter(w/ lens off) and clicking the shutter over and over until I saw
the problem. I did this on the film side of the shutter too.