That's an unacceptable rate of wear. I would push the dealer for a permanent solution, and contact Triumph if it isn't resolved. Sounds like you could be in for a whole new wheel. Take a look at this thread from the archives:
Cush drive woes! I haven't seen many complaints lately on the board about this problem, but ya never know when it can crop up on the odd bike or two.
FWIW, I have just over 30,000 miles on my Speedmaster and I'm starting to get a small bit of play in the cush drive. Wehn I take it in for the valve adjustment at 32,000, I'll get a new one.
