turbo dude

i was just jumpstarting it

the bike is hooked up to the battery in my car..it's fully charged. i checked and cleaned the ground (earth) to the battery. i took the starter apart and cleaned/sanded the brushes and the commuter? should i get a starter rebuild kit or buy a remanufactured one?

i'm trying to fix my buddy's virago and i need a little advice. i did some research and it looks like the virago has a history of starter problems because of the way it is designed. my problem isn't the typical grinding problem though. the first thing that happens is it keeps blowing starter solenoids. so to get the starter to engage now i have to short out the connectors on the solenoid itself. when i do that the starter seems to want to turn the engine over but just doesn't have enough power. every once in a while it will work but 90% of the time it clicks but won't turn the flywheel. now i took the starter off and tested it and it seems to turn freely. is it possible that it's just worn out? i've never had this problem with a starter on a car before..it either works or it doesn't. this starter will turn fine out of the bike, but once i put it back in it doesn't quite have the juice. what do you guys think?