Starter sprag clutch exploded periodically, a well known problem.
Wonderfully long motorcycle for tall guys (I'm 6'-6").
Not great performance, but pulled like a truck. I fitted a Peter Furlong chain case, which was a huge advantage over the standard open chain.
Here's my tip; WHEN your sprag clutch explodes, don't go to Ducati - it's common with a Borg-Warner auto gearbox part and costs sod all from an autobox supplier.
The sprag clutch should be thrown away and a "vee two" sprag clutch purchased from Brooke Henry at Vee Two in Perth, Western Australia. He has his own version which will last forever. As with any other engine matters, talk to these guys first.