The pump is driven by the sleave that slips over the crank and sits on a chamfer on crankshaft. It is then nipped between the crank timing sprocket and the vibration damper hub by tightening of the retaining bolt. In your first post you said you had retightened the bolt, i stupidly thought you had torqued it correctly, obviously you did not. There is a special tool for holding crank against rotation whilst tightening the bolt. It is not difficult to make an alternative. Holding with the TDC pin would be a last resort not recommended and could lead to tears. I have done this in the past, but not on this motor, only on motors with a slightly more substantial lock pin.
PS IF you are going to be doing a lot you may find getting a Sealey VSE5538 set an advantage. Around £80.00 and free post on net if you look around.
Sorry - I didn't realise it required quite that torque. When I tightened it I only nipped it really.
Anyway......... Tonight I have tightened it a bit more (against the 12mm timing pin as advised not to) and the oil light seems to have gone out. Going to get a bit better access by removing the rad cowl etc and get a new bolt to be on the safe side before tightening properly.
Thank you all for your ideas on helping me sort this problem (which in the end was found to be caused by me!)
Does anyone know the dimensions of the crank locking tool - outside and inside diameters, number of holes and PCD would be great?
Rob