I know that a plastic substitute would not be ideal but you might want to consider a 3D printed version as a temporary replacement.
If you have the original and possibly damaged part someone local could likely scan it and print a part.
If you don’t know anyone doing something like this do a search for a local “Makers Group” and they would likely be thrilled to take on the challenge.
Some of them are also into machining and might be able to mill you a billet part.
Before all that though, have you checked with Randy in case he has what you need?
Good luck