The Air Cadet® Pump Service Kit contains a pump head with two PTFE valves and two Noryl® retainers permanently installed and one diaphragm. The top of the pump head must be removed to replace either the diaphragm or the pump.
To replace the diaphragm, simply unscrew the old diaphragm by hand. Screw the new diaphragm into position, making it hand-tight. Extreme torque is not needed or desired. An internal stop prevents it from being screwed in too far. If the diaphragm is not threaded completely into place, the performance of the pump will be adversely affected.
It is a good practice to replace the head with valves and retainers whenever the diaphragm is replaced. Do not disassemble the pump housing from the motor. Proper assembly (factory-adjusted) is critical for proper pump performance.