Help with slide out

We just bought new batteries. No luck.
Husband says it's not a hydrolic system. It's mechanical. Do you think there is a relay in this type of system?

There is a high temperature cut off relay in the circuit that could be defective and interrupting the power early. They are usually mounted on the wall of the battery compartment with the wiring to the hydraulic pump. Mine started doing this some on an older (~10 year) trailer, not because of the relays, but probably because the rubber seals were old and stiff. The problem was worse in cold weather.

If you have a generator, start it and see if you have the same problem. If you don't, it's most likely your batteries.

Bill

Slides basically are powered by your battery....Is it fully charged and in good condition?