Hi mgarvin4,
When the hydraulic pump is energized, it can run in one direction to extend slides and landing gear. It can also run in the other direction to retract.
Each device or set of devices has a valve that opens to allow fluid in to extend the device, and out to retract. Some trailers may have a separate valve for each slide. Others may have a single valve that works for all the slides. When the valve is closed, no fluid can pass. So when you extend the slides, as you release the button, the pump stops and the valve closes to lock the fluid in place, holding the slide open.
Normally, if you press the switch to extend or retract the slides, that switch signals the hydraulic pump to run in a particular direction and also signals the appropriate valve to open and allow fluid to move.
If there were an electrical failure such that the pump didn't run and the valve didn't open, you could manually open the valve and use a drill to operate the pump. In the case where the pump runs, but the valve doesn't open, operating the valve manually lets you extend or retract the slide. Just remember to close the valve so the fluid stays in place.
I would think the switch inside the coach signals both the pump and the valve. If the pump runs when the switch is pressed, I'd check the backside of the switch for loose wiring.