Genuine STAXX Part #28030303 WH-25S-H Pump Piston

The pump piston is seated to the rear of the hydraulic unit, a pump spring and spring cap are positioned over the pump piston, the spring allows the piston to move up and down.

The handle then sits over the spring cap, when the handle is pulled down this compresses the spring and pushes the pump piston down into the hydraulic unit, this forces oil through the hydraulic unit to the lift ram piston allowing it to lift.

Fits Staxx models WH-30S-H, WH-25S-H

Part #7 on the diagram