Sounds to me like the cross shaft between the gears broke--is yours a Lippert frame?
Most of the slides have one side pushed out by a ram or electric motor, and the other side is a follower connected by a cross shaft. If the slide moves out/in, but one side doesn't seem to want to stay even with the other, that is probably what broke. Need to cut into the belly cover along each of the slide arms to see if the cross shaft is turning on both ends.
'16 40QBH Phaeton
'15 38RSSA Mobile Suites--traded
'05 36TK3 Mobile Suites--retired but not forgotten