Thomas S San Ramon , CA November 15, 2015 One of the bottom rollers was broke from wear Could not use the screw head to hold the roller while turning the nut. So end up prying the roller and ball bearings off the shaft and using a vice grips to hold the shaft while taking the nut off. Thereafter, very simple to install this new roller. I did the pair as the other bottom roller would likely fail soon too Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes