77-80 door panel trim rings

[xbanone]

I bought a set of 77 door panels from the classifieds here to use in the retro-fit of a set of power window/lock '86 doors onto my '76.

During disassembly of the door panels, everyone of the studs on the back side that hold the trim ring on is breaking, these studs are plastic and 36 years old. Is there anyway to save them? Is there a source for new ones? I have seen the inserts but not the trim ring itself.

Here are the door panels in question.