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JLG 400S Platform Only Rotates 1 Direction 2007

Joined
Oct 14, 2022
Messages
11
Location
Sandpoint Idaho
I have a 2007 JLG Boom Lift. The platform does not rotate or rotates very slow to the right(intermittent changes when machine is shut off) and but work fine in the reverse direction.
The boom lines were recently replaced. (The lines run continuouse from the main control valve to the rotate actuator motor assmebly. No internal check valves). The control valve coils for the platform rotate were replaced. The platform rotate actuator was replaced. The platform rotate check valve cartridge was replaced.
After the platform rotate actuator motor assembly was replaced and that did not fix the problem I spend a good deal of time troubleshooting this problem.
When I reverse the lines to the platform rotate actuator, then platform will not turn the opposite direction.
When I swap the platform rotate lines with the platform level lines the platform rotates in both directions but the platform level function will not work in one direction. This also will reverse when I swap these lines. Plumbed one way it will not tilt up the other way it will not tilt down.
No change when I swapped the platform rotate control valve assembly with the platform level control valve assembly.
When I swap the electrical plug that actuate the control valve coils the controls are reversed but the platform continues to not rotate in the same direction. No change in direction of non rotation with the controls being reversed.
The ground controls produce the same results in all cases
I swapped the platform rotate relief valve cartridge with the platform level cartridge with no change.
When the plarform attempts to rotate the pump pulls hard and the appropriate line to the actuator moves with pressure. The platform will spring back.
It is like the line has pressure but the pressure is not allowed to go back to the reservoir.
I do not know what I am missing. Any help would be appreciated.
 

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