Whenever someone begins contemplating a DIY repair on a Canonet QL17 I refer them to the photograph at the beginning of this thread.

After paying for a professional CLA all of the moving parts in my QL17 now function correctly and like new, and I'm extremely satisfied. Also, the lens elements and rangefinder are now internally cleaner than I ever thought possible.

However, I would be remiss if I didn't also suggest reading the entire thread, as apparently not everyone else had the same good experience that I did.