Hi. I have a 97 Astra TDi with Izuzu engine. It keeps leaking oil from the pump on the back of the alternator. I have had two reconditioned alternators complete with pump fitted. The second replacement has just started to leak from the small air hole where the pump fits to the alternator body. Is it likely there is a blockage somewhere causing a build up of pressure and failing the seal? Has anyone any ideas please before I take the alternator back again?