Hello - The lower of the two rollers on each side of the tub that create the channel for the rack rail appear to be coming loose. This is causing the rail to fall out from between the two rollers and the top rack is no longer stable or upright. Is it possible to simply replace those rollers or does that require a new tub?

Thanks for the tip. I took a look at the wheel assembly and it seems the wheel assembly is just fine but the hole that is tapped into the plastic tub is stripping out and will no longer allow the screw on the assembly to grab much and therefore it is tilting over and allowing the track to slide out from between the two wheels. Is there a patch or plug that is possible to use? Maybe a larger screw size for the wheel assembly? They could not possibly expect us to have to replace the entire tub if one wheel assembly strips out of the plastic.