Replacing roller on slide

I've figured out at least one of the reasons the front slide is so difficult to move on our newly acquired 2004 2720SL. One of the front corner rollers is missing (the one against the far wall, closest to where the chair normally is). I assume I can get a replacement roller from the factory, but how do I go about getting under there to install it?

I also noticed that the rubber strips on the tongue that the slide rests on when in the closed position have a fairly well defined 'crush zone' about halfway through their depth where the slide sinks down into them. Is this normal?

Thanks.
--
Allen
04 2720SL