K,
Bob is right. The two versions of the pump can be rebuilt if they are not too far gone. With the older, large style pump, it's usually the sealing that fails.This pump usually only requires new bearings, brushes, a cleaning of the main bellows seal, and replacement of some other o-rings. The newer, smaller pump is much easier to rebuild because the sealing system is much simpler and their are no ball bearings to replace. If the commutators on the armatures are worn through, the pumps are good for parts. Cores usually run anywhere from $25.00-75.00.
George Des