Hi Guys
Thanks to you all for the advice which I put into practice and the yoke finally surrendered to me. I had a bit of a problem when the puller shot off, after a few alterations and a few good whacks with the hammer I had another go, then after a loud crack the puller started working easier and the yoke came off. The old oil seal was next and the seal puller I purchased made the removal easier. I am now ready to fit the new oil seal and put the whole thing back together. It was suggested I pack the shaft and seal with RTV sillicon before putting the yoke back on, I guess that should solve the problem of the oil leak.
Cheers
Tony