Hi, sounds terminal. My advice, go and ask Jack Daniel what to do. Know what I mean. You ain`t gonna get any sense here at this time of year!!!!!!
But, seriously, this does sound pretty damned terminal. I wopuld think that, at least, you`re going to have to split the crankcases and have a look in the gearbox. Sounds like a big job to me.
Best wishes and Seasons Greetings to and yours, which ever God you may worship.
Let`s stop the fighting and all buy Bikes
Rob Chamberlain and Family.