You might want to look up MIMF. He frequents the site and works for Lippert - manufacturer of the slide system. There have been some issues and he may be able to help you. In the absence of your dealer being able to fix it, you may want to get ahold of Montana directly. Just a couple of suggestions.
Ron and Terrie Ames with Sirius - MOC #1920
2015 Montana 3160 Legacy Package
2019 Ram 3500 Laramie Longhorn
4x4, SRW, SB, Mega Cab, Pullrite 2600 Hitch
TaxMan, I've had slide problems and I taken my unit in two times. Rv Connections told me that the seal on the bed room slide needed to be pulled out a little . I also installed toppers over all the slides.
Have your seals checked.