500cm mirror return position

I've had a weird light leak on my 500vm for a while. It's not a dark slide leak (happens on two backs. I've replaced seals on both. I thought it was loose backs, but they aren't very loose.
Here's an example of the leek. It is square edged, and inset into the frame
I sent it off for a CLA, but it does still happen. I thought I had it under control by making sure the latch for the back was fully pushed across, but this morning I noticed something.
I don't think my mirror is fully returning. When it's up it is very slightly hanging down at the front corners, more so on one corner than the other. I can put my finger under the mirror and push it all the way up. Pictures attached. Also included a side view showing the edge. To me it seems like it should really be all the way up so that the edge is all the way into the baffle.
Can somewhere compare to their own camera?
Also, any tips on a good service option in the UK? I can reach back out to the guys I used, but I'm not sure if their up to the job now.
Could it just be that I need to adjust the housing a bit?

Is one option.

Another user on another forum posted a picture of their mirror and it has a similar lean at the front, and even more so than mine. They haven't noticed any light leaks so this may be a red herring and it might just be down to me needing to properly push the latch across.
It'd be great to see pictures from other users though. it feels like it is designed for the mirror to be as flat and level int he baffle as possible.

That's not a light leak but a shadow. Not a full obstruction since there an image in the shadow. Whatever it is, it occurs in the bottom and right of the camera body.

However, there is a brighter region after the shadows. But this could be development surge?

My mirror sits flat. It can be pushed a little bit against the foam when it's up but it springs back.

The bright inner region is, I believe a leak, that leak is shadowed before it hits the neg though, causing that hard edge. Here's one where I cropped the outer "shadowed" square area so that I could get some usable image for someone. The "shadowed" outer edge is correct exposure, the leak is getting shadowed. (sorry, I don't have the pre-cropped version to hand without re-scanning the neg).
Until I noticed the funny angle of the mirror up position I had assumed it was a leak where the film pack meets the camera (and being more conscious latching it seemed to help, but may have just been me convincing myself). If it is the back then the hard shadow makes sense as it would be the shadow of the edge of the open "film gate" .

I don't think the shadowed region is the correct exposure since the intersection of the bands (top left in your OP) is darker. There is another darker square top right, as well as a fainter shadow on the right side (I just noticed it).

Does this occur on all frames? How is the rebate area around the frame? To rule out development issues, have you had issues with 120 film from other cameras?