Thanks Barnett,
What I don't understand is the York was new when i had it installed 10 years ago. It leaked within 2 years and possibly within 12 months. It was just out of warranty when I had the seal replaced the first time, and has leaking periodically since then.
It got worse and so now I have stripped it down and removed the seal, the shaft has rust pitting and has caused damage to the seal!
I can't understand this in sealed unit, perhaps the quality of steel used is not as good as earlier?
Anyway, looking at options, wondering if anyone has tried or got thoughts on me installing a Speedi Sleeve on the shaft and trying that for a couple of years or longer if successful?