Elroy also has a Hein-Werner floor jack,model WS. Several years ago it needed service as well. Discovered that service parts are available. In fact every single part is available including the major castings. Enough parts to completely build one from scratch. However this would would be cost prohibitive. Elroy procured his parts from Waltz-Dettmer in Cincinnati
http://www.waltzdettmer.com
At one time they were a Hein-Werner distributor and Elroy would think they could point you in the right direction.
That takes care of the parts. As far as service is concerned, any local "Hydraulics" shop worth their weight should be able to handle this. Be advised these cylinder use "leather" seals and they don't last forever. Your jack is worth fixing and if you don't want to fool with it and decide to discard it, discard it in Elroy's direction.