Not a great deal of info online for the trailer group, so some questions may help sort a solution. First stop is what kind of slide movement? Is it the type which has a motor at each side that turns a gear moving along a track?
Sounds correct from your description of buzz at one side but not the other!
Next step may be a bit harder. On many of those there is a way to work from the inside by pushing a rubber flap that covers the gap between slide and main body over enough to get to the small motor? Do you see something like that? For location, I "think" the motor will set just above the track you see when slide is open. Big heavy duty rubber flap that seals the crack when the slide is open?
IF this is a corrrect guess so far,there are times when the motor wiring pulls down too hard and the solder joint on top of it goes bad! Or the motor may be bad?
But on a happier track, there is likely to be a slide controller onboard somewhere. I think of them as a small plastic "box" about 4X6 and a inch or so deep. Likely hidden away out of sight. Some are in a nearby compartment or some on the bottom of the slide where you can't see it now!!
If you can find this controller, it may allow you to unplg wiring going to the two motors and swap as a test that it is actually a motor or wiring problem and not a problem with the controller.
Do we trust AI info yet? Sometimes it does good, sometimes not!
It sometimes quotes what we are discussing on the forum as a reference????
But this seems to be more reliable than some!