Check the electrical connections on the solenoid for that jack. Have someone hold the manual extend button for that jack and check the led lights on the control panel. The HWH web site has a trouble shooting guide for reading the led lights for possible electrical problems. A quick way to determine if it is a bad solenoid would be to swap a known good solenoid into that position. If that works and the problem follows the solenoid, you've solved your problem. The solenoids just screw into place and are easy to swap out with little or no hydraulic mess. HWH should replace the bad solenoid under warranty, if that is the problem.
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