I think they're electric/cable and, if so, my main slide does the same thing. It's very disconcerting but I had it checked while on the road this summer and the technician could find nothing specifically wrong with it and offered no solution. I thought it was going to up and quit working! I have noticed, from the outside, the cables appear out of adjustment as they no longer pass through the center the round holes in the metal frame of the trailer but have been migrating inwards, cutting the metal and now the holes are elongating inward which makes me very nervous. The cable is remarkably not fraying or anything but I will be taking mine in to the shop for a more thorough check and maybe realignment.
If I'm wrong and yours are hydraulic, I apologize for carrying on
I would love to hear what yours are doing more explicitly and if you come up with anything.
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Paul "Poppy" Cervone
2015 Grand Design Reflection 337RLS
2011 Cougar High Country 299RKS - SOLD
2007 Silverado 2500HD Duramax/Allison CC 4x4
2007 Corvette Z51
2009 Cadillac CTS