Interestingly, I'm finding out that you can, indeed, remove the TDU without dismantling the engine. It can be removed after removal of the rear wheel, bevel box and drive shaft housing. However, I think mine is a little past that.
It 'might' be under warranty? Ity WILL be under warranty just as mine will be.
Triumph seems to have a problem going on that needs to be addressed and not here in this country but rather in England.