Builder-grade sheave degradation
That matters for rollers because builder-grade steel rollers with plastic sheaves were standard through the 80s and into the early 90s, and thirty-plus years is about the ceiling on those before the sheave face flakes or the stem bends in the track. What you pay depends on what's actually on the door: whether it's still the original 7-ball steel roller, whether someone already upgraded to nylon at some point, and whether the track itself has enough wear that rollers alone won't fix the noise.
