Leicaflex SL viewfinder window issue

It had to happen, a forty year old camera new to me can't be all perfect. The viewfinder window fell out! Ahhh!

Fortunately, I heard it hit the floor, just thinking I had kicked a pebble or something, walked on about 20 yards, found a shot to take, raised camera to eye only to find a very blurred image. Logic told me maybe that sound might have been it, and sure enough, went back to the spot and found it. Even more miraculously, upon study, found that one 'wing' was missing a tiny fragment, maybe 8mm x 2mm x 3mm, so looked for that, not really expecting to find it, but found it in about 5 seconds!

So I've got the parts. The camera has a 6 month warranty, and I know the sensible thing is to send it back. That involves a trip to London and train fare expenditure, when I expect all they will do is what I can do. I can see that both 'wings' have been broken before and glued back in place, so will be susceptible to future breakage. What I can't work out is how it stays in place when fitted correctly (and it plainly doesn't). There are v shaped recesses on the wings that I assume sit on the metal spike (see (not very good) photos). I guess that you just push the viewfinder on and it 'snaps' in to place, with the v's held by the spikes?? but I'm not sure. I can effect a repair to the broken wing, but I don't want to chance leaving something inside the body, if it breaks when I push on. If this is fairly simple, I can do it and secure the shoulders of the window against the metal of the body as a fail safe with carefully cut double sided tape or a very tiny blob of some appropriate glue. Or a couple of nice self-tappers ;0.

The other option is to just stick it back by the shoulders only, as with only one complete wing in place, it sits back in its correct position quite readily (but is able to fall out), due to the fact that you can put it in at a slight angle, and one of the v's sockets onto its respective spike. The spikes seem to have some limited freedom of movement to the L/R, so I'm wondering if there is some trick to this, like hold out the rewind lever, push down cold shoe, slaughter a goat?

Anyone know how these are supposed to fit/function?

TIA