Rear door knobs

[mdwyer]

I was thinking....inserting an appropriately sized piece of dowel into the hollow threaded shaft of that knob, and gluing it in place there, would eliminate this problem altogether.

I did very close to that. I epoxied in a plastic pen barrel -- it was the only thing I could find around the house that fit so perfectly! It's been sturdy ever since.

Perhaps filling the hollow shaft with epoxy would be effective preventative maintenance on the other three.