This is a static solution for the sagging back plate problem. print these replacement parts to sturdy up the homeophone. It will require 4x 5mm (or sae equivalent ) screws and nuts. because of the stand design you will need varying length screws.
I designed this but have not yet printed it. I print most things in .3 mm the holes in the base will be blocked by a 1 layer sacrificial bridge.. use a screw or drill bit to clear it out of the way.
hope this makes the whole thing more sturdy.