The Ax-7 had a minor accident - plaguing keytar is a contact sport after all. 
Forgive my serious lack of experience in repairing, so my attempt to explain may be a bit off but here it is
The mounting for these keys is individual - a spring in the back provides for the return, and towards the front of the key is a square bracket under the key that hooks into a plastic piece the stands off of the plastic that runs underneath. This also has a rubber bushing that fits around the piece of plastic on the standoff. Since
the standoff is broken off there is nothing to hold the key from popping way up above the playing surface.
Any hacks out there to get the key to stay put ? Does not look like there is a part for this. /see attached pic - the mount for the bushing is there on the right key but broken off the one on the left.
