Thank you, I understand more now. The first washer does have remnants of a rubber-ring, I thought that the rubber remnants had just stuck to the first washer due to being pressured against an O-ring for six months.
So it seems I need to:
1. Find a new washer with rubber-ring. Amel only?
2. Find some more thin washers to try and adjust the V groove to be vertical while the bolt is also tight. I don’t like the mastic idea much, I’d rather it sealed properly with the O - rings. I have a suspicion that the material I thought was a perished O-ring was in fact some mastic which had been put on when the V bolt was fitted. (I had too many other tasks this year and asked the technician at the marina to fit my ropecutter. I thought it was a straightforward job that didn’t have much chance of going wrong!)
3. Replace the shaft seals regardless of them showing any problem. We have 1065 hours.