Welcome. Problem Komatsu PC180LC-6K left-hand travel motor.Does not have the strength to move backwards,forward moving normally.
1) Pilot controller 2) Shuttle valve? 3) Relief valve 4) Swivel joint seals 5) Counterbalance valve on motor If you can identify and switch the two pilot lines, this will reverse control input, if the problem remains the same (weak reverse), the pilot system is okay. If you can identify and switch the two travel motor hoses at the control valve or swivel joint (above the swivel joint) and the problem remains the same, then you either have a problem in the swivel joint or motor/counterbalance valve. You can swap the two relief cartridges in the counterbalance valve and see if that changes anything. Or take pressure readings forward and reverse.