Dave,
It is normal for the pump to make a whirring buzz sound. If it is really loud, it could be that some debris got between the vane and the lower plate of the pump scuffing one or the other or perhaps even both. You might try removing the lower plate and taking a look. If they are scored, you may be able to smooth them out by taking some fine valve paste compund and lapping them on a piece of plate glass. If this is an old style pump, it may also be that the ball bearings are running dry . If this is the case, the pump will have to be totally disassembled and the bearings replaced. Hope this helps.
George
