140 models with the aluminum window frame are the easiest. Carefully peel the rubber seal off the aluminum frame, remove the bolts that hold the frame to the door and the screw that hold the vent window and channel. Lift the works off the door and access to remove and install the window is direct. The new lower window channel has to be forced onto the glass along with the filler strip. I set the window on a wood table top with an assistant holding it upright while I hammer the channel onto the glass. Just be sure to install the channel facing the right way and in the same original position. - Dave