The first step in fixing an inoperable RV slide-out is to troubleshoot the cause of the problem. One common problem is that the slide does not respond when switched on. This often is fixable by replacing the control switch.
If the power switch works but the pump does not power on, it may be necessary to replace the key switch. If the pump powers on, there may be a problem with the retract valve. The valve, located along the slider components, may be broken in two pieces or it may be too worn out to seal properly. The solution in this case is to replace the valve.
If the pump operates but the room does not retract, the wiring or the retract valve may be bad, and need to replace it. Also, if the room does not open, the problem could be a bad control box or a broken solenoid valve. Observe these parts when operating the slide, and replace whichever ones are not functioning.
If the room moves back out after it is closed, the solenoid valve or manifold check valve may be leaking or malfunctioning, in which case they need replacing. If the room is moving in after it extends, check for an oil leak, or replace the solenoid valve.