Swapping a bottom seal or lubricating a track, most owners can handle on their own. Springs are a different matter - a torsion spring under load has put people in the ER, and on a door built in the early '80s the spring is often mismatched to the current door weight if anyone's touched it since, which makes DIY riskier, not safer. Full installation is a two-person job with the door, jambs, and opener all needing to line up square, and if your house is on that older end of the 1983 build range, the opening itself may not be as square as a newer frame. Our honest limit: we don't do the install if the existing jamb is rotted or out of plumb past what shimming can fix - that's carpentry work, not a garage door job, and we'll tell you to get that fixed first.