I have a 2006 Navigator. I have the same kitchen slide mechanism, although my kitchen is on the passenger side.
On my motorhome the slide was never properly adjusted. There are 2 rollers under the floor, one at the front end, one in the bay where the fuel tank is. The rollers at the rear of the slide are cheezy, as they are under the cabinets under the sink and have no capacity to carry the some of the weight of the slide. My slide at the rear end dragged on the bottom of the slide opening and failed to touch the gasket at the top. My painted stripes matched up perfectly.
I had a local rv shop replace the slide mechanism but they set the slide so the paint matched, which put extra pressure on that arm to push and pull. At home I loosened the attachment screws ,which are a real disappointment when you realize they are carrying the weight, jacked up the slide so it fit the hole like the front and the reattached the mechanism to the wall. My stripes are now about a 1/4 to 3/8 off, bu my slide works beautifully smooth. I would like to add one of those heavy rollers under the slide at the rear the same as the front. There is no good reason these things should have left the factory without that slide having rollers underneath all the way across. All the other slides have them!