Genie Z60/34 steering problem

I'm working on a 2002 Genie Z60/34. Serial# Z60-3844 I'm having problems with left steering, it locks up and don't want to turn left, it will turn right. If I move the forward/reverse joystick while moving fast enough I can get the wheels to turn left Things I've checked and replace I've check voltage from joy stick and have 13.6 volts when turning left but no steer, followed wire #36 all the way to the floor panel and have 13.6 volts. So I followed wire going to the steering distribution manifold and have 13.6 volts going to the solenoid. So it's not electrical. I replaced the steer valve on the manifold to no available, replaced steering flow regulator valve on main manifold to no avail. Repaired both steering hydraulic cylinders (both were leaking) no avail. And lastly replaced the oscillating hydraulic cylinder as it to was leaking as well to no avail. This has me stumped I've checked and followed Genies trouble shooting process and all I'm left with is to replace steering manifold and if that doesn't fix it to contact Genie. So for you experts what might be the problem? Something I missed in my trouble shooting procedure? I don't have gauges, but are on the list, any special fittings I need? If so what are they and what size do I need? Thanks in advance