Thanks Grumpy,
Just to clarify I haven't been holding the mower stationary on slopes , with the clutch , an unduly long period but just briefly when I'm navigating around trees and obstacles.
I have also followed the manual's recommendation to use forward pressure on the pedal , at low revs, when going forward down slopes to allow the engine to assist braking.
I do have some steep slopes, but these have never bothered my 26 HP Twin before.
I had another longer inspection of the drive system earlier this morning and nothing is obstructing the clutch linkage and the belt and pulleys all look fine.
The dealership did put what I would regard as a hell of a lot of grease on the chain at the service but it doesn't appear to have been flung onto the clutch.
The cork on the front drive disk is a little more worn than the reverse disk but still has plenty of meat on it.
I'll undertake the procedure you described and get back to you.
It's great to have someone with knowledge about Greenfieds to assist. Thank you.