A homeowner with the right ladder and some patience can swap a chain-drive opener on a standard door without too much grief. Where it goes wrong is the force and travel limit settings - set too tight and the opener fights a door that's slightly out of balance, which burns out the new motor inside a year. In a cold-climate build like this one, where garages see real winter load on the springs and track, an opener that's fighting imbalance from day one is a short-lived opener. If your springs are original to a mid-1970s build and they haven't been serviced, that's worth a look before a new opener goes in, not after. Pulling the old unit down safely, especially if it's wired into a switched circuit rather than plugged in, is the other spot people get hurt. We're not going to tell you it can't be done. We're telling you where the failures actually happen, because we see the redo calls.