By test the circuits, I assume you mean pressure test?You are wasting time swaping parts. Your lack of function is not caused by bad cylinders. Something is wrong with the plumbing. Test the circuits!
Dan
Looking at parts on SurplusCenter.com to put together pressure gauge assemblies that I can plumb inline and curious how many I should build & install. I assume I want one on the "in" side of the valve, one on the "out" and one each on the A & B ports if I want to test out the lift cylinder circuit?