Yes, all four of the rollers appear to move.

What it really feels like is that there's supposed to be something just under the trackball apparatus that holds it up slightly, and whatever that thing is, it isn't there anymore. When you push down on the trackball, it doesn't give at all. I saw another thread about cleaning some sticker that resides under the trackball. Is it possible that that or something else fell out when I took the first trackball out?