To remove the sump, unscrew the two mounting bolts and withdraw the oil pump, tilting it to disengage its sprocket from the drive chain. If the two locating dowels are displaced, refit them in their locations. To remove the drive chain, first remove the crankshaft sprocket, then unbolt the crankshaft seal end cover from the cylinder block, recovering and discarding the gasket if applicable, as a new one will be required on refitting. Prise out the oil seal with a screwdriver and discard it, as a new one must be fitted on reassembly; the new oil seal may be fitted with the right-hand cover on the bench if necessary. Slide the oil pump drive sprocket and drive chain from the nose of the crankshaft, noting that the drive sprocket is not keyed to the crankshaft and relies on the pulley bolt being tightened correctly to function properly. Unhook the drive chain from the drive sprocket. Clean the components and carefully examine the chain, sprockets, and pump for any signs of excessive wear, recommending renewal of all components as a set if evident. Before refitting the oil pump, prime it by filling with clean engine oil while rotating the pump clockwise. Wipe clean the oil pump and cylinder block mating surfaces, checking that the two locating dowels are fitted in the cylinder block. Engage the drive chain with the drive sprocket, then slide the sprocket onto the nose of the crankshaft. Fit a new gasket to the end of the cylinder block and refit the crankshaft seal end cover, inserting the bolts and tightening them to the specified torque setting. If a new oil seal has already been fitted to the cover, wrap tape around the nose of the crankshaft to protect the oil seal, removing it upon completion. If there was no gasket fitted to the cover, apply a 2.0 mm wide bead of silicone sealant to the cover sealing face, ensuring the bead runs below the bolt holes. Tilt the oil pump and engage the sprocket with the drive chain, then position it on the dowels and insert the two mounting bolts, tightening them to the specified torque. Finally, refit the sump.