Calibrate Apex Cart shelf - shelf not moving

How Do I re calibrate a shelf on an Apex cart if it gets to it's lowest position but will not raise up again? Troubleshooting non moving Apex

Have customer do the following if the shelf is not moving:

- Can you plug it into a wall outlet to make sure its not a power pack issue?

-Can you check all connections from the handset / control box / column and power supply and make sure everything is tight and secure.

Have customer do the following if the shelf is stuck at the bottom:

-Hold the DOWN button until it's fully lowered. Release the button.

Press and hold the DOWN button for 10 seconds until you see/feel the cart squat about 1/4 inch. It is now reset.