Torsion or extension: which one is on your door
Look at the wall above the closed door. A torsion door has a steel shaft running across the width of the door, with one or two tightly wound springs on it and a cable drum at each end. The springs twist as the door closes and turn the shaft to lift it.
An extension door has no shaft. Its springs run alongside the horizontal tracks above your head and stretch as the door closes. Each one should have a safety cable running through its middle, so a spring that snaps stays on the cable instead of flying loose.
In our job records, 12 of the 13 spring repairs with a recorded type were on extension springs, and all seven new-door jobs went in with torsion springs.