What is really interesting is page 11 of the Lippert In-Wall Slide-Out Owner's Manual:
It is recommended that when operating In-Wall® Slide-out system in harsh environments (road salt, ice buildup, etc.) that the gear racks and seals be kept clean and free of debris. They can be washed with mild soap and water.
Note: No grease or lubrication is necessary, and in some situations may be detrimental to the long-term dependability of the system.
However, I can tell you by experience that lubrication is absolutely necessary. My slide would groan and pop and struggle. Finally, when pulling it in, at the end of movement there were two loud pops. The bottom gear on the lower rack of the rear of the slide skipped several teeth. Unit purchased brand new 3/23/2021. Now there is 5 teeth of the gear rack showing on that corner when the slide is all the way in.
I lubricated the rails with the dry silicone lube with PTFE and even though the slide-out room is now misaligned, the slide out is running out and in more smoothly than ever before with no popping, groaning or straining. Absolutely lube the gear rails with the proper lubricant! Lube every 90 days or if you notice it is especially dry or the slide out starts expressing itself again.
Unit is going in to the nearest dealer that will fix it - 300 miles one way.