This is a slide-out platform that slides into the space above the knee-hole of my desk. The metal channel on one side won't let the whole thing slide forward. I sprayed it with a little WD40, but it only moved a tiny bit. Any ideas?

If a ball bearing has broken it may not allow the slide to work. Look tor an obstruction in the track.

Thanks, I'll look, but I don't think there are ball bearings in this apparatus. I think it just slides on a channel. I'll check it out. But I'm kind of scared to take it apart.