Not sure if this will help but my motor is labeled (pic below):
0136 350 008
JRA <-> 12v 1000W 3100 1/MIN
S2 10 Min
Made in Germany
I googled Bosch 0-136-350 and got a hit on a motor that looks like ours, I think, although it's labeled 0-136-350-011.
Seems like we should be able to get inexpensive stock brushes, but I didn't spot them.
Good luck hunting,