If the small unloader (bleeder) valve on or under your pressure switch leaks constantly AFTER the unit shuts off, replace this part. The check valve is a one-way valve that prevents air from backfeeding from the air tank.SpecificationsNPT - 1/8"  X 27...

Piston / Cylinder kit to restore compression. Includes air compressor piston rod kit with compression ring, cylinder cup, and o-ring seal. If you have a sudden loss of performance, replacing the cylinder sleeve and piston ring usually restores...

Campbell Hausfeld air compressor pump head kit includes the bare head, screws and washers, and head gasket.