Yikes. Seventeen rollers. That is the same number as in the size bearing used for the rear linkage for the shock. So, possibly it is a medium small bearing. I hope someone recognizes it.
Considering the age of the bike, unless you have a very economical shop or your good at taking down a bike engine, the end of life might have arrived. Whatever bearing it is, it has to have access to the engine sump.
Did the shift works feel okay? Any strange noises or difference in anything?

 

That's the answer. I drove it for 500km without it. There doesn't seem to be any other damage, but I have to remove the oil pan to get the rest of the parts out. View attachment 39453

 

That's the oil pump drive chain carrier bearing that sits behind the clutch basket. So hopefully not a complete engine disassembly.

 

I didn't know needle bearings would fall apart like that.... until I found out

 

I can see how vibration in the clutch could stress this bearing. Will be interesting for the final result of your exploration. When you get in there, the oil pump (driven by chain with its sprocket riding on this bearing always looks loose when tension set correctly. Just so you can not push it to the left and hit the case.

 

Clutch basket bearing? It was upgraded in the latter models.

 

The clutch basket bearing is much larger and no reports of it coming apart. The oil pump bearing is about the size of the photo parts. I'm not aware of a new main inner basket bearing up grade by BMW . There is a bearing available that is more durable.