[Carl n Susan]

Plus it controls the jacks in addition to the slides. So when it quits, and it will, you can really be SOL. Each use diminishes its life span. Cold weather causes the hydraulic fluid to stiffen up and makes the pump work harder, which draws more amperage, further affecting life span. As BB_TX wrote, they are cheaply made devices. Life span is measured in years so failure isn't imminent. But 6-8 years is a common age when they quit.