| Frank,
Your problem is not the sprag clutch. When the clutch fails the starter turn OK but doesn't turn the motor. i.e. The clutch slips.
I think you should be looking at connections from the battery to the solenoid and from the solenoid to the starter. Particulary the terminal on the starter which collects a load of road muck under the rubber boot and is susceptible to corrosion. Check also the earth cable from the battery -ve to the frame connection and don't forget to check the terminals of the frame to engine earth cable which is beside the crankcase breather, hiding behind the RH footrest hanger.
If all these connections are clean and making a good contact with no improvement, try bridging the solenoid terminals with a large screw driver. If the motor turns over quicker then the solenoid is faulty. Possibly burnt contacts inside it.
If none of the above gives any improvement I think you should be looking at the starter motor itself, probably brushes. Which I believe can be replaced without removing the starter. (Haven't done it myself though)  |