The plunger bore is tapered. If you try to jamb the leather pump in there dry, it can turn inside out and be useless (think sexual connotations here ). Get the leather seal soft and lubed, and be careful it does not turn "inside out" during a hasty assembly. Inside out will not produce the required pump squirt.

Scott B. "I'm a self-made man... I started with nothing, and I still have most of it!" 68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph 69 340 GTS stock 14.18@ 95.60 mph 01 5.9L Ram 1500 Quad Cab 4x4 01 3.5L 300M 16.23@ 86.97 mph