Big bearing behind the pulley mounting surface. It is a triangular piece of steel. It presses off. Behind that is a NTN TMB303 bearing. 17x47x14 and behind that is a STEFA viton shaft seal 19x32x7. Then there is a "wall" and you must flip the pump over and remove the 6 bolts. In there , there is 2 o ring which I do not know the size of but they are definitely readily available. Prob cost 20 quid for them all looking at ebay. You would need a press and behind the triangular pulley mounting piece of steel there is a shoulder of casting that actually overlaps the bearing outer race. So the way to do this would be to press of the triangle puller mounting face and then dremel around the shoulder ( there is a casting line you can follow) then press then shaft and bearing out from behind and then follow our nose from there. I didnt get to do mine because I actually broke my casting in the press because I did no know what way it was structured inside. Know for future now. The bearing will go back in perfectly with the shoulder removed and the shaft seal does the sealing so that shoulder is not necessary.