Hi, there are a few fortunate classic stove enthusiasts who never see the rear side of an air pump. Their non-return valves (NRVs) are never irretrievably stuck, and are easily extracted from the interior of the pump tube using the appropriate tool. This post is primarily for these lucky people, and illustrates what is on the hidden side of an air-pump. This is what is revealed once the air-pump is de-soldered from the tank and then further dismantled: You will note the lead washer designed to be inserted between the head of the NRV and the base of the pump-tube. This is often absent from stoves, and this is part of the reason why NRVs seize in situ. This lead washer spreads and seals on tightening and there is a groove on the base of the pump tube to help accommodate and locate it. Happy fettling. Best Regards, Kerophile.