I know this is a little late to the game... A few years back I had the same problem with the boss on both the engine and the outer case crack and drop the gear and shaft out of position.
My solution was to run a pin though the hollow shaft that holds the gear, drill a 3/8" hole in the center of each boss and reassemble. Coincidently I had the cover off for the first time last weekend and everything is fine, no wear or loose pin. I think it was a couple $100 when done, maily because I bought another engine cover and drilled that, the boss on the original was badly torn up and I was concerned it wouldn't hold. Anyway, I have added 15k miles to the bike since then including a trip to Key West and back with no issues.
Considering I was being quoted for a new engine plus labor ...thousands of dollars, I thought this was the better alternative.
