That needle bearing in the clutch is probably the weakest point in the whole system.............
Thanks for mentioning that. Thinking back about what I saw, I realize you are absolutely right.
There are no seals which should keep grease in place and in contact with the needle bearings at all times. I found quite a lot of old grease between at the center part of the housing, between the needle bearing and the sealed outer bearing - but the needle bearing itself was running almost dry.
This means most of the grease actulally migrates inwards - towards the center part between the bearings. Therefore the needle bearings eventually start running dry.
My intention is to check, clean, and re-grease the needle bearing at least every 5000 km.