You need to take your volt-ohm meter and find a good ground point, not on the slide. Then run a wire from that ground to the common input of the meter. Then check the light sockets for ground or power. Ohms between the good ground and the outside of the socket and volts between the good ground and the center pin on the socket.(make sure the switch is on) This will give you a starting point. Then you know what you are looking for.(power or ground) If you don't find power or ground, I would suspect a plug has become disconnected.
You may have a connector or terminal strip under/behind the couch check it out. May have been bumped. If all that checks out. Find where the power/ground wires enter the slide and check for damage or loose plug.
Since you have this problem on two slides, check for a place where the wires meet.(Are both slides on the same side?) The power/ground may feed through one slide to the other. OR there may be another fuse block or inline fuse. But I'm guessing from here on.
Please get back with what you find. Good Luck!!
