Andy, I think it'll be an awful struggle to set the timing up properly and keep it there if the key is dead like the parrot. But it might be possible to unflatten it as follows: take a 7.8mm drill or length of anything rigid, insert the blunt end up the hole. Grind or file something down to get into the small gap you've probably got where the inside of the raised bit for the key has got squashed, and prise gently against the drill's shank to try to get it back - without busting the thing, as it's quite delicate. Jeweller's screwdriver might get it started. You really want the raised bit back for all its length if possible, using a tapered square section spike - with extreme care - driven in against the drill's shank to keep it on line.
If no joy, I've got one old brass plate you could have - the key's good but there's slight wear on the pivot for the moving point, and it's also missing the little push-fit brass pin that holds the moving point's retaining clip on.
Send me a private mail if you're still stuck when you've tried to unflatten the thing. If you've got all the other bits, something can be done, it always can. Not quite sure what the 'plastic baffle(bin)' is though!
In all events, I think you'll probably have to reset the timing, as it'll be a bit out whatever you end up doing. Loctite on the centre screw could be a problem too - it's only 4BA and loctite's quite strong stuff. Fingers crossed you can get it off again!
