Right now would be the worst time to sell for you, you could very well get years of trouble free work from it once everything is maintained correctly as you seem to do. It's just one of those things and you won't have to worry about the transmission for a long time.A fellow over the road has paid out 20K on a Deutz and still has an unreliable tractor. We could work with one tractor as the Class has done the entire harvest on it’s own.
It is a twenty year old tractor that might not be finished causing trouble.
I half knew a man in the UK who would buy fendts with broken varios, fix them and run them on very successfully afterwards