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.
This procedure requires an important communication dialog between the rope operator and the pipe vise operator.
The rope operator's job is to pull hard on the rope to take up the slack, and announce that they've "got it," to let the vise operator know that they're holding the weight of the riser main.
The vise operator will then announce "loosening," and loosen the pipe vise.
The pipe vise operator then announces "tightening," and tightens the pipe vise.
It is now safe to loosen and remove the tripod pipe vise.
Be sure to loosen and then fully remove the tripod pipe vise from the riser main. Sliding it down the riser main will scratch the pipe, creating dangerous sharp grooves and causing rust.