I am a new Hayter Osprey owner having snapped up one that was for sale in the next village to us and of course the usual internet search for information was initiated soon after collecting the 'Beast'. Hence finding this forum.
As far as I can tell a previous owner replaced the original engine with a 12hp version and that seems to have serious grunt.
The clutch friction material was pretty well worn down but I managed to find Custom Brakes and Hydraulics in Sheffield and sent them the clutch plates and they sent them back with new friction material bonded on, more or less by return of post.
This is what I have bought and already it has more than earned the modest purchase price by clearing overgrown parts of our paddock.