Just to let members know.
developed an oil leak on the pump end plate.
took it off and the o ring had gone hard and oval
it was replaced with a carb manifold o ring , was a little bit smaller but stretched to fit.
That O ring believe it or not is a standard metric size - 45 x 3.5mm. You can order them from a bearing supplier. If you specify the replacement to be Viton rather than the standard Nitrile you won’t have any problems for a long while. A bit more expensive but well worth it.