Unfortunately, Lippert has built so many variations on the hydraulics that it's hard to know where all the valves are and which does what. Sometimes the landing gear valves are located at the landing gear. Sometimes they're at the trombetta (which is like a distribution manifold attached to the pump). The valves for the slides might be the ones with knobs.
Check the landing gear first to see if the hydraulic hoses go to valves at the landing gear. There'll also be control wires going to the valves. If not, you may have to locate all the individual valves at the trombetta.
If your slides have individual switches, there will be individual valves. If a single switch, there could be one valve, or perhaps several. If you have a 6 point leveling system, I think you may have 4 valves: one for each front jack, and one for the off-door-side center/rear jacks, and one for the door-side center/rear jacks.
We do have some of the
Lippert manuals here. Maybe one of them will help you find the right valve.