Hi Steve,
The window needs to be removed as an assembly and then the frame is taken apart to access the slider window. If your so inclined to tackle this, it is a two man job as the window is removed from the coach.
1- Remove the window treatment, valance, ect. 2- remove all the screws from the inner clamp ring going into the window frame. 3- apply masking tape on the outside to orient the exact location for rassembly. 4-run a razor knife around the perimeter of the exterior frame thru the sealant. 5- push from the inside either upper corner to start the window to pull away from the sidewall and have your helper get a grip from the outside. 6- visit your local glass shop that does automotive window repair. Good luck and Regards, Fred