first off you'll need a 5000psi pressure gauge with the correct QD (female) connector to connect to the test port on the function control manifold.
go to genie's website to the manuals section and look up your machine by model and serial number. The service literature will have all the information you need to check pressures and determine which circuit the problem is in.
Keep in mind, if this is an older unit there may be multiple circuits affected.
Most of the time when i run into this type of issue when so many functions are affected it winds up being bad orings on the solenoid valves and check valves etc.
You may have to pull each one out and check them one at a time for any damaged orings or stuck valves that may have trash in them.
Also remove the inline hi pressure filter at the propulsion pump and check it for debris like rubber from deteriorated hoses or oring debris. This filter is encased in a black metal housing that screws off. (make sure you turn off the main gate valves at the hydraulic tank supply lines so the hyd fluid will not drain out when you have the filter off.
Make sure you have something to catch any oil that leaks out onto the frame, it will and it can get messy.
Once you complete this if you do not find any issues with orings or bad valves then you will have to start considering checking the electrical functions side of it.