Mike,
I have the same model and year and there are 2 screws in each vertical trim board. There may be Velcro behind them, as there is behind the horizontal board at the top. It is tight, but you can see the mechanism when those are off. To check the rollers, I had to raise the slide from the outside and work over the seal to access the roller. There was only one on mine, but I have added two, one at each end. If the roller covering (rubber) is stretched, take the roller out (mechanism operates like toilet paper holder where one end compresses into the center). Replace the rubber with 1 1/4" PVC pipe pressed onto the roller. Much cheaper and more efficient than the rubber which means you have to buy a new roller. You need skinny arms and a very large screwdriver lever to do this. Others have taken the slide out, but very hard to do.
Roy Warren