Repairing Leica Lens Catch

A friend of mine has a 35mm summicron which has been used to the point that the little slot that the body locks into has worn on one edge into a bit of a slope. This allows the lens to rotate off the body without pushing the release button.

I'm just wondering if anyone had experience with repairing that and advice about how to go about doing so.

Thanks!

Likely to need replacing the mount.
At your own risk, file the slope back to ninety degrees. This will probably cause misalignment with the focusing cam.
If it's got exposed brass maybe a jeweler could build it up with silver solder and then file it square.