A Newmar is not likely to have a Lippert slide since, as far as I know, Newmar only uses Newmar slide mechanisms.
Sounds like one of your trans torque bushings got loose and slipped a little. It's pretty simple to loosen and adjust the bushings. Here's one write up from Newmar
You can find others on the internet and YouTube. Just be careful and don't loosen the bushing while any part of the slide is on the slope of the ramp that raises and lowers the slide on any flat floor slides.
When seconds count, the police are only minutes away.
2023 Grand Design 2600RB, 2013 Nissan Platinum Armada tow vehicle, Titusville, FL when not on the road