Before performing any repairs, perform a water test on the pump by raising and lowering the handle a full 40 strokes. A properly performing pump will yield greater than 10 liters.
Remove the hex head bolt from the top of the access door on the pump head.
The following procedure requires two people. If you attempt to do this alone, you risk injuring yourself and damaging the pump.
Lift the pump handle until the base of the chain comes to rest on the spacer collar, and the chain is slack. Hold the handle in this position while the chain is being detached.
Use a pipe vise to unscrew the first section of riser main from the coupling.
Be careful not to remove the coupling from the lower section of riser main. You may need to use two pipe wrenches to hold the coupling still while you loosen the top section of riser main.
Lift the section of pipe straight up from the coupling.
Be very careful to hold the pipe as straight up as possible. If it bends or falls over, it may damage the pump rod, or injure someone. Always have at least two people holding the pipe.
Take note of the direction of the foot valve in the end cap. This is extremely important for reassembly, as the pump will not work if the valve is facing the wrong direction.