ummm, yes and no. Pb used several types. I think you have either a "C" cat or "CF". Either way the up/down valve is in the right rear side of the tub. It is about six inches square and about three inches thick. It will have two kiinda round coils showing with two wires to each. Depending on the version, there are different looking coils and valves. You can start the cat, lower the tiller(do not start the tiller) engage the down pressure, and hold a wrench up to each of the coils. The "hot" one will draw the wrench. Then, switch to up pressure and see if the other coil holds the wrench tighter. If so,(it will be obvious) the coil is either weak or just shot. If you want to use down more than up, then just switch the coils for a while or e-mail me a picture of them and i can send you a new one. Be sure to check, and clean the ground connections too!!
paul