ok, after allowing renaut to try differnt oil in the gearbox (with no change) to try to eliminate a slight 4-3 crunch, they would appear to be willing to change the box. (Less than 7000 miles)
Tims box was full of metal deposits after drag stripping a few times, and 3 that I am aware of have disintegrated around the clutch housing / input shaft area causing catastrophic damage to the gearbox casing and the engine mounting flange necessitating new engine and box assembly.
How do other owners of 172 and cup find the change on the box ??.
I would be interested in your experiences and comments.
A clutch problem has been ruled out leaving only the box as culprit btw..