Factory nylon roller type
That matters for rollers because these doors mostly shipped with factory nylon rollers on stamped steel tracks, not the older steel-wheel setups you'd find on 1980s stock. Swapping a nylon roller is within reach for a lot of owners: unplug the opener, secure the door, work one roller at a time so the track keeps its shape, and don't touch a roller near the bottom bracket without releasing spring tension first.
