On these old units, the pump is similar to an old boat bailing tube. The gear system is attached to a simple stroking rod which has a pump ring at the end. The pump plate has leather sweeps attached to cause suction....bringing gas up from the tank. On the down stroke, there is a way to release pressure in the same area. The rod goes up and down inside a brass cylinder. This is a very basic machine. If you don't want to take it apart, try some automatic transmission fluid? It might work? Let it soak a while. There have been times, when I have restored these old pumps and no matter how I tried to get them to move.......I have had to tear them down to accomplish the results needed. Paul www.severngaspumps.com