Sorry for not replying before. Have got so much work and study to do and even cleaning cameras is a nice distraction!

It still requires brute force but after mounting and unmounting a few times and letting it sit overnight it isn't as much as before.
I might try the screwdriver trick... By the way, trying to unscrew the mount is about impossible, none of the screws will unscrew! The older 28 and 135 will, but this one not... It's as if they were superglued.
Rebending, I tried a couple of soft hits to the table, won't do it for the moment.
And once I need something properly measured or repaired I feel it, almost no proper tools! I tried measuring as per shutterfinger but A steel ruler can't get close into the mount and depending on the viewpoint one sees a differnt measuring mark.

Given that I tend to use mostly this lens, I don't need to change it that much and at the moment it's alright. Functionally it's fine, good focus and fine diaphragm. The problem is IF the lens has become misaligned... Seemingly not, infinity focus is fine when focusing through the viewfinder.
These older systems are tanks, anyways