Any mechanical part and especially an electro-mechanical part will wear out. It is not at all hard to replace the brushes and lube the surfaces to get another ten years out of them.
C'mon Vette, it's not that scary. You can get brushes from the dealer, but it's a lot cheaper to go to the hardware, find similar brushes and gring them down to fit. I've done it a number of times.
Try the starter when it's removed from the engine before disassembly. If it doesn't work, what could it hurt to try to reapir it?
I wish I had checked if it worked when it was out before ripping it apart. The brushes were a pain the the rear end though. When I finally got it put all back together, and hooked up the battery starter/charger to my battery and tried to start her, the electric motor began to smoke worse than the inside of Snoop Dogg's van on 420. lol. Now the motor won't even turn at all. Oh well, I never used it anyway.