Hey Hipshot,
You may recall the problem I had with my starter switch at about 1 year old. The contacts in the moveable portion, that should have been 'floating' on a spring, were embedded in the plastic during manufacture. After some use, they were not making good contact and began to arc and burn, accelerating their demise.
I was fortunate enough to get the 'stealer' to agree that it was a manufacturing defect (even though I was a month out of warranty) and they got another for me at no cost.....except, I had to let them install it for a half hour charge, $35. You can't buy the switch by itself, you have to buy the entire throttle block with harness....$85. Needles to say, I was prepared to manufacture my own switch block and floating contacts!
Anyway, my point in posting.....I have found most starters can be brought back to 'like new' by simply cleaning the carbon from between the commutator strips. This does entail removing the starter and taking it apart. The only tricky thing is reassembly, holding the brushes back while putting the winding back in place. Oh yeah, when taking it apart, be sure to have your hand wrapped around the end with the brushes, or do it inside a plastic bag.....this will prevent you from having to search your garage for the little springs that will go flying to who knows where. Be sure to lightly lubricate bearing surfaces and apply a thin coat of silicone grease to the 'O' rings before reassembly.