b717doc - This also happened to my 2005 Speedmaster. Local bike welder fixed it up better than new. Added a little extra beef around the idler gear shaft boss. I discovered later though that to make sure the boss was perfectly aligned he had drilled and tapped a hole into the crankcase to hold the shaft in place while he rebuilt the boss. When drilling the hole he got just a smidgeon too deep and actually drilled a very small hole through to the other side just above the starter motor. This caused me no end of confusion for several days trying to find the source of the oil on the floor. When I did discover it I was able to take advantage of the drilled tapped hole to run a bolt (can't remember the size) through the shaft and screwed into the tapped hole. I put a little hi-temp silicon on the bold first, cut the head off the bolt. No oil leaks since.
I had to replace the clutch cover. All total the repair was about $250. Once I had the clutch cover back on I removed the oil sump and did an oil flush just to get any tiny bits out. This was in May 2011 and the bike has run perfectly, no starting issues and no oil drips. Good luck!