It could be a resetting breaker causing the slide not to work. If your slide used to go part way and stop, and then continue after a moment, the breaker was resetting. These are known to eventually fail, needing replacement. They are normally close to the battery, small square box shaped, with a heavy wire. On my FW, it is mounted just inside the basement wall, but only about 18"s from the battery.
Keep in mind, a well charged battery is usually required for slide operation, even if hooked to shore power.
Jerry
