One- (1) roller broke and did not allow the top pull out tray to pull out.

I first removed the plastic stops holding the upper tray on the tracks. Once the stops were removed I removed the upper tray and replaced all four- (4) rollers that were easy to snap off the tray frame. Once the rollers were removed I replaced them with the set of four- (4) new rollers. Then replaced the tray onto the tracks and replaced the plastic stops.