In trying to replace a missing screw to the center of the overflow tube faceplate, I discovered what may be a major problem.
Normally the screw goes through the center of the faceplate and into the back of the overflow tube. When screwed tight it, pulls the overflow tube tight against the back of the tub (and gasket) creating a tight seal.
However, the place the screw is supposed to be received into the overflow tube is partially broken and has 1/2 of a rusted screw solidly wedged in there. Even if I could get it out, the overflow tube would not receive a new screw.
Is there any way to fix this situation creating a tight seal without any major reconstruction to the bathroom or destroying the living room wall, opposite the back of the tub?