Hi Jeff, It's usual to do an INTRO "new members section" BEFORE you ask a question , just polite to introduce yourself before asking strangers for information, we are NOT grumpy about it but like to get to know you before some will answer your question. It's not an uncommon mistake for new people to make so if you would be so kind as to do an INTRO we would be much obliged.
As to your actual question, it sounds like you starter motor brushes are shot, easy to do once you have the motor out, also check that the ARMATURE is not worn (copper rotating bit that the brushes rest on) if it is worn then you can either replace the whole motor or take it to your local engineering works and they should be able to recut the faces for you, will not be the cheapest fix, other wise get a second hand motor from Ebay or such and put new brushes in it before you install it. Hope that helps?
PS Welcome to the YOC, always nice to have new folks join in and help others out.