Ouch! That doesn't look like an easy fix. Two methods come to mind, however. Both ways seem like they would work best if you can remove the rubber mounts from the gimbal base plate first.
1) By hand, wet the rubber nub with saliva and insert one side into the hole, then using pressure from your other hand's fingers, push the rest of the rubber tab into the hole, working around from the edge that you got in at first.
2) Use a small screwdriver or pin punch in place of your fingers in method one.
Using method 2, it may be possible to accomplish without removing the rubber mounts from the gimbal base plate, but I wouldn't bet on it.
Good luck & please update when you get this resolved!
Thanks
Jim