Don't rely on your extended warranty plan. I had one on our last Lacrosse and when my slide motor bracket bent they refused the cost of the repair. Depending on which warranty company it is you may or may not have a problem getting them to pay. Also, if you had a dealer "perform an annual inspection" of the affected component or not may come into play too.
For me, the Lacrosse was in its' third year and since ALL components were working flawlessly, I never had reason to "take it in". So, when the slide apparently got bound up and I tried to manually get it to move, I bent the bracket that holds the motor to the frame. When my dealer contacted the warranty company, they refused because I had no records of "preventative maintenance/inspection" on the slide.
Disconnect the "RAM" under the slide from its' bracket and the slide should be free to move. Push it in, block it in place and get it to the dealer before your original warranty runs out.
I would also e-mail the dealer and call putting them on notice that there is a problem and you will try to get it to them A.S.A.P.
Good luck and keep us posted