i had some starter trouble a couple days ago, because of the starter solenoid disengaging. it turned out to be a burnt contact (between the big+wire that goes to the motor to the little one on the solenoid , that litle piece of metal).
So, while having the starter off i decided to open it up and check. To my surprise i found lots and lots of little plactic pieces that came from the part that covers the 3 small toothed weels (pic). I had it done from bronze,including bronze sleeving of the holes that hold the 3 small axels. I guess it won't die again
The only plactic part remains the fork that the solenoid pulls on. If anybody is intrested in the AutoCAD drawings for it, let me know.