An air hammer that responds slowly or does not start when its trigger is pressed may have a worn throttle plunger assembly. This small moving assembly works inside the throttle valve to help control compressed air entering the tool. Check the hose, air pressure, trigger, seals, and nearby valve pieces before choosing a replacement. Confir...Read morem fit with the complete tool model because similar plungers may differ. Shut off and disconnect the air supply, then release stored pressure before service. Keep small springs and seals in order, use only the lubricant named in the service manual, and test the trigger carefully after reassembly.