No clue exactly on yours, but a lot of slides have the actuating motor/mechanism on one side and a long metal tube/bar going to the other slide. One side (motor) is the leader, the other side is the follower--the motor turns the gears on the one side and the tube/bar moves the other side. A shear bolt is usually in play to make the tube turn with the motor shaft--if sheared/broken, the follower side won't move. Can figure this out by opening the belly cover in line with the slide arm back far enough to view the motor/gears.
Best I can think of.
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2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired