FWIW, we have experienced pretty much the same thing with our Berkshire,
Out of four slides, the dining room was slow to slide out and even slower to retract.
Put it the shop before Thanksgiving and they just called and said after going back and forth between the coach manufacturer, the slide manufacturer they finally found that the problem was it faulty hydraulic ram on the slide.
donnie(K7UTA), Linda, and 2furrykid s Buddy & Rain
2016 SouthWind32VS, 2014 Jeep Cherokee Limited