Well my diagnosis was correct so I have a complete strip down to solve the problem. I'm going to lap the gear onto the taper and fit the key with the same love and attention that I apply to half shafts. It really is a bloody awkward place for a tuppenny component to fail.
Oddly I'd never heard of this problem until it occurred to me!
Charles
Oddly I'd never heard of this problem until it occurred to me!
Charles