Well I've found an epoxy glue designed for metal to metal that is said to be extremely strong (270 kg/cm2). Since I have no way to access the screws to tighten them even if I manage to remake the holes, I'm planning on gluing directly the surface of he rotating disk of the rear standard to the base plate where the holes are located. I probably won't need to de-install it if I manage to make it work fine glued.