Joan - I rec'd two jack screws with my 211-S that I use when my slide is brought in and ready for transport. The dealer did not make much of an issue with them, implied that most owners did not use them. These jack screws can be placed between the frame of the B+ and the lip of the slide. By turning the middle portion, the slide is pushed inward and pressure is applied to the exterior seals. I questioned the value of this myself, but have been doing it. It could be that your unit needs these jacks, if it did not come with. Some B+ bodies and some slides may be twisted ever so slight and need this additional pressure on the seals. I never place much tension on these as I do not want to flatten the seals when the unit sits for a couple months.
How many others have these jack screws and do you use them?
Gene
Model 211-S with 5.7 Chevy