Does anybody have a drawing of what the trigger mechanism of the 52D looks like inside? I have a drawing of the C trigger, but the D I own is slightly different.

xs headspace:

The Win 52D had some inherent problems with the trigger/safety. You could put the gun on Safe. Pull the trigger. Then push the safety off and the gun would fire. I believe they made some changes between 62 ans 62 to correct the problems. You might check the U.S. Pattent Office they should have drawings on file. Most of which you can pull up on the internet.
Good luck
Longshot