Not knowing exactly what is wrong with your slide, I was visiting with a rep from factory who said the original electric motors were too small to handle the weight--fix is to install new larger motors. Not sure why DRV/dealer would not know this if it is the problem. May be to simple, or not your exact situation.
And, as Motor31 said, you should talk to DRV direct--they are very aware of this problem as I have talked to several new owners with same deal.
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