Yeah, sounds like you need to pull the starter motor out and disassemble + clean it out. If there's still some life left in the brushes it will buy you some time before you need to replace them and it will give you a chance to find the right ones on ebay and get them sent to you. A cautionary note - starter motors can be stubborn once you've freshened them up and assembled them. It may take a couple of test fires on the bench before it wants to kick over every shot (I'd recommend bench testing it prior to installation as it can be really frustrating not getting any signs of life from the starter once it's bolted up)