I learned a little more about the large slide during my recent visit to Nappanee. The factory was unable to spare a man or the time to take a look at my slow-to-close slide, but they did send me over to Dave at RV One.
Dave is very knowledgeable, but quoted over $500 to adjust the slide. Gulf Stream of course balked at any assistance, so I had to pass on the adjustment.
What I did learn however, is that the slideout should be adjusted to "droop" a little in the extended position. That is apparently accomplished by supporting the slide to the ground & loosening, then adjusting the 2 supports & the hydraulic rod. The supposed reason for this is to give a better attack angle of the slide floor against the high density nylon to raise the slide for insertion into the room. Do I believe it? I don't know & don't intend to tackle this myself. Dave said there was sufficient room for the seals to still work properly. I really don't want water problems.
The discussion however got me to thinking & making a more careful inspection of just how the slide works. I can see where a significant amount of force must be applied to cause the angled leading edge of the particle board slide floor to ride up and over the angled nylon bar &/or the painted steel bar under it attached to the main coach floor. I have no idea if I did a good thing or bad, but I had a bottle of liquid ski wax lying around. With the side in & lifting the rug, I was able to slop up the leading particle board floor edge with wax the full length all the way back to the actual bottom of the slide floor. This is the surface that rides against the nylon when the action just begins. Next, with the slide extended just over a foot, I was able to stuff a wax-saturated, cloth covered wooden paint stirrer in far enough from the outside to really cover the full length of the nylon bar.
Did it make a difference? For now, slightly. Once over the hump, the room always moves quickly. When closing up, the trick of "bumping" the switch to "out" then back to "in" continues to be the reliable solution, even with the wax. I no longer go outside and push the room as I can coax it with the switch.
I also asked Dave about pressure adjustments on the pump. He didn't want anything to do with that as a solution.
I'm sure that lubricating the rails is important, but if the problem is only for the 1st couple inches during closing, you may want to look into making the "raise-up" interface a little slipperier.