Bedroom slide, no stop!

[KarenG]

We have an issue with the bedroom slide. Extending out and pulling in, at least half the times the slide gears do not stop. The slide stops at full extension in or out, but gears continue and you can hear the rapid clicking, although I'm very careful to watch for a certain marker I have to know the stop points.  Sometimes, when pulling the slide in, I need to lift the bed and start it manually with a turn of the socket wrench,  then it will operate and pull in. 

How do I determine the real issue?

What are best maintenance routines & products for gears?

Thanks for your time and input!

(Photo is from a different slide but shows the mechanism.)