Sorry to hear that you are all having slide problems with your 28BHBE, back in April when I took delivery the slide worked fine once for the PDI. Immediately after that once I go to the campground the rear slide gear lost a tooth and the slide would not extend (or retract) properly.
After TWO trips back to the dealer, the issue was resolved. The first trip they replaced the gear, but did not realign the slide, so I took it back again and they did the realignment...I was not particularly happy about the quality of their repairs.
Now that the slide is working "properly", there is definitely a gap from the inside floor of the slide to the floor of the trailer. This gap is a few inches and is almost equal across the whole slide, a bit less in the middle. After inspecting the mechanism for quite a bit of time, I strongly suggest that none of you use the slide when it is retracted. This will cause lots of problems and a Jayco technician said to not do this.
Otherwise, the slide has worked relatively well since it was repaired the second time. I do see some movement from the wall in the center of the slide when it is being retracted; I would prefer not to see that but when it is extended it seems sturdy, and I am heavy ~275lb.