Those pumps are pretty bullet proof, I've still got my original with just a center seal replacement about 20 years ago. A couple of tips: Disconnect the cylinders from the top frame and then you can cycle them up and down. Also, if you need to add fluid, leave the cylinders disconnected and pull the reservoir plug and fill to the bottom of the hole, cycle the system up and down several times to purge any air in the lines. DON'T over fill the reservoir.