Thought replacement process would be fairly easy, but it's not. The cylinder is press fit into tank, have to hammer it in with 2x4 and hammer. Even lubricated, is very tight fit, o'ring seal did not seal final assembly so tank fluid leaks out bottom when pump pressure begins to get to 10psi or so. Cheaper to buy new unit.
I remembered how difficult it was to replace just the diaphragm several years ago and read that the whold pump and cylinder was quicker and easier to replace. It wasn't.
