New seal on the gear change shaft seems to have cured it!
The oil leaked rom the gear change shaft; the first photo shows the oil about to drip.
On removing the cover, again the oil was coming from the gear change shaft seal, marked "A" on second photo.
Main drive sprocket shaft seal seemed to be perfectly dry ( & now signs of oil flinging up&around fromthe rotating shaft, tends to confirm it).
But what I also noticed to the front of the drive sprocket, was a rubbing mark on the casing; ("B" on the photo)
The chain rivets have been just kissing the case.
I now realise that having used a modern 530 o-ring chain, that it is wider than the original seal-less chains!
I don't know if anyone else has seen that problem when fitting modern sealed chains to old Jap bikes?
I've decided that it isn't going to get any worse; I have inspected the inside chain rivets and side-plates, but they all look fine).
I've done 10miles around the block to test for oil leaks, & she seems to be free of leaks!
- Yessss! result.
So no need to worry about then main drive seal for now.
Andy C