Unicomp redoes the rivets like factory.
Unicomp opens the case, removes the guts, and puts in a new set of guts.
You will have a 2015 Unicomp keyboard in a 1988 IBM case.
Not from what they told me on the phone. They said they have the barrel plate as a part and can replace mine as part of a repair. He even mentioned I could do it myself with a bold-mod, but theirs will be sealed the same as factory.
I have the feeling your barrel frame is really damaged badly. Not only on the front side, but in the back side too. You probably lost the rivets holding the top part of the keyboard together. That explains the "droop" of the key to begin with. It's probably not clicking because there is not enough tension between the barrel frame and the back plate.
In any case, you can try to band-aid it, and see if that will fix it. However, you will still have the same problem with the barrel if there is a chunk of it missing. The hammer behind the F12 key may be out of alignment with the barrel frame, and the membrane may (or may not) be damaged.
It's really a question of what you want to do with it. I hope you get it working.
F12 was clicking fine before I took out the stem to check for a cracked barrel. It was just my retardedness of not paying enough attention to detail to noticed that the spring would move out of the stem as I placed it back in the barrel.
I'm not sure how bad the rivets are, but the rest of the board feels great, just like the one I'm typing on now. I really wish whoever slung that board and had it impact the f-row so hard that it broke barrels would have been more careful.
At some point I plan to open up all my M's, and check them over. I still haven't fixed the one that has the num/cap/scroll lights not working that I posted on here about a year ago.
Their time will come. I'll also photograph them all in their full glory, before and after (because the before will look yucky!).