Well, some good news...

Tried another go at scraping away the glue, but did get too far, got right in there with my macro, and can it's pretty gunked up, so I couldn't get anywhere - Some research pointed at repair stores using a varnish to stop them coming loose...

Out of sheer frustration, I went back to scratch with the unjamming process, and winding on the gears manually... aaaand, it got the mirror down, and recocked the body. Wow. I don't think I left out a sigh of relief like that in a long long time.

As Mudman said though, I'm going to invest in another body, I'm not happy at all if I can't fix something myself, ie, the varnish.

Thanks for the help folks... Thread seems pointless now, but I'd been working on it since last Tuesday...