Have been having a potential problem with the starter kicking in when button is pushed, but hear a squealing prior to engine turning over. Haven't taken apart, but sounds like a clutch is not engaging as it should. could it be the overrunning clutch and are they available as an item from Harley?

 

Pull the starter and check it out, its sounds a little like the over-running clutch is slipping or the solenoid not engaging properly.
I believe the clutch is a replaceable part as its listed as a subassembly in my parts manual. It lists several different part numbers however so your going to have to figure out exactly which one you need before you can get the right one if its really screwed up.
If its the solenoid the manual lists a repair kit for that.