We last ran this advice in June 2014, but Gary and John in Support asked that it be run again. Always use the Mast Bolt every time you raise your Message Board. By doing so, you take the pressure off the hydraulic system, and thus can prevent leaks.
Just as you would not use a hydraulic jack to lift a car without also using jack stands (ok, John admits that he occasionally does this while working on his cars), you need to secure the mast with the bolt. The bolt is included in the plastic bag in the compartment containing the controller. Once you’ve raised the mast to full height, secure the mast with the bolt as shown in the photos, then finger tighten the nut.
Think of it this way: The mechanic at your garage wouldn’t lift your car to work under it without first securing it with a bolt, pin or other restraining device, so don’t you skip this important step either… for your own safety and to protect the sign from damage.