Finish Thompson DB4V-M621 Pump Repair Parts, with DB4 Series PVDF Sealless Mag Drive Centrifugal Pumps Exploded View. FTI Part Breakdown, Diagram & PDF Manual. Replacement Impeller Assembly, Housing, Thrust Ring, O-Rings, Screws, Bushing. Motor, Adapter, Flange, Barrier, Drive Magnet, Retaining Rings, Bolts, Washers.