Welcome to irv2, jnickf
Below in my signature you will find links to many answers for your Newmar.
Is it coming up the ramp OK when extended?
You need to be plugged into shore power or running the GEN the motor needs a good 12v to operate.
You may need to increase current to the control pot for motor.
This link will lead you to all TSB's, brochure, owners guide and much more.
QT's # 3 has PROBLEM SOLVERS threads one being slides.
QT's 1 & 2 have all slide info, jacks, AC's and much more.
Hope to see you on
the forum, enjoy and safe travels.