When I had a SOB just like the MPG the slide was a screw type/auger style rod ran by 12 volt power that moved the slide out.
On mine the kitchen was in the slide, the cabinets on that slide out had at the bottom inspection panels to remove and that's where the motor was.
So, once you see the motor there was a nut on the end, and you would use your wrench that's used for your stabilizer jacks to manually turn that nut that would turn that screw/auger rod that would slide back in or out the slide.
Like I said..... this was on a SOB travel trailer, I mean "IDENTICAL" to the MPG... wont mention brand but it was called a RPod.
Don't know if that's allowed to say the model, but that is what it was.
I'm sure it has the same set up! Hope this helps ya!........