From my understanding the function of these slide rollers is critical. I suspect that because they are made of some form of high density nylon with a thin stainless steel rod, that like all setups with similar bushing effect on a thin shaft will over time start to bind. I see no indication of a silicon grease being called for because there is no way to grease them and oils and nylon with no way to clean the inner surface do not mix.
I am thinking seriously of replacing them before they start to bind as all nylon bearings do after years of slow heavy wear. There is considerable down force pressure on these small plastic rollers.
I can plainly see that they can easily become the first failure point in slide out function because they could start to bind very quickly indeed if the center pin starts to cause the plastic to fail as a roller bearing. It is not the same as the good old school heavy babbitt bearing system on steel rails that were used for the first slide out designs and cannot be greased.
Unfortunately my bearings are the most expensive ones on the market.. but that just comes with the territory I guess, still putting a third on on might also be a good idea to lower the load pressures and prolong the nylon bearings life because it will be a longer surface area of rod to nylon contact. The very last thing that we would want is for our slide out to start binding and cause that nightmare that so many have happen with these types of trailers. So this is essential preventative maintenance that is completely undocumented IMO.
I would imagine if I took the trailer to a dealer the 98 dollar US per bearing costs for three new ones plus the shop labour would hit us with at least a 500 dollar bill just to change out these bearings. We are not sheep though so putting out good cash and doing it ourselves is the best option.
From what I understand, to change the bearings all that is necessary is to slide out and then gently up wedge the bottom of the slide in line with the bearings so that they can be replaced. Of course no ham fisted hammering of wedges just enough so that the weight of the slide out is taken off the bearings.
Here is a link to the component we will need three of to accomplish the service for anyone who might be having issues with bottom rollers on their slide out starting to fail.
Ours have not failed but I can definitely tell that soon they might because over the past 3 seasons the slide has slowed down a little even though I do service the rails correctly as per maintenance instructions in the lippert manuals. So the bottom rollers are not as smooth as they were a few years ago.
https://store.lci1.com/j-38-roller-320500
Here is the roller location on the trailer with this particular design.