The gearboxes are a pretty simple design, however there isn't much you can do without splitting the cases. When I first read this, I thought to myself it was either the shifter return spring, or a bent selector fork. Either way, it will be covered under warranty, it's just a shame you have to be without it for a while.
The mechanics are right though, very seldom are there major problems, so you must be lucky.
Mick
