I believe you have a generic Lippert slide mechanism, electric only, no hydraulics? If there are teeth on the slide arm, then the motor turns a gear on the one slide end and the square bar turns the gear at the other end. There are 'pins' (usually just threaded bolts) that lock the square bar to the round shaft ends. These pins are there to 'shear off' if an obstruction it hit when the slide goes out/in so no permanent damage is done. Clear the obstruction, replace the pin/bolt and operate the slide. Many times, the slide ends will be out of sync and you will need to turn the slave end by hand/wrench. Probably easiest to use a pipe wrench on the round shaft to move the slide end in/out to where it is in line with the driven end. As to the top/bottom alignment, there are adjustments on the end of the slide arms for that.
If the motor works, then you probably just need to replace the pin/bolt in the driven end and sync the other end and put the pin/bolt in that end (assuming the square shaft is usable). The shaft should be a 2-piece slip fit...smaller one goes inside the larger one to adjust the ends to where the pin/bolt can be put in.
2016 Tiffin 40 QBH
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2005 TK3 #1869, 10 yrs of memories,
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2009 F450 4x4-died; 2010 F450-retired