On doors from this era, the panel itself usually isn't the only thing wearing out. Steel doors from the 1970s and 80s run thinner gauge than what's made now, so a single dent from a bumper or a basketball can crease the panel enough that the section won't sit flush in the track anymore. Wood and wood-composite panels, more common on the older end of this stock, take on moisture at the bottom section first, and once that panel starts to swell or delaminate, it drags on the rollers every time the door cycles. Hardware mismatch is the other issue: replacing one panel on an older door sometimes means the new panel's hinge spacing doesn't line up with the original hardware, which is a hardware swap, not just a panel swap.