Starter quit working today. Turned but did not engage flywheel. Removed starter and it bench tested fine. Stuck my hand in the starter hole. Teeth felt fine, but I found this in hole. What the heck? I figured it's part of the t o bearing, but the clutch works fine, and it shifts fine. I didn't realize there was brass in the bearing.

It looks almost like a seal that has come apart, but don't see how it could be a seal or bearing because it is still a concentric circle (although beat up) so anywhere it would be would require it to break to be loose like that.....Hmmmm...let me go look at mine.

Starter armature shaft end bushing and retainer. Came off the end of the shaft.

That makes allot more sense. It looks bigger than that but it makes sense since anything else would have to break apart to come off the input shaft of the transmission.

My deductions exactly!