Did a spring break? If yes:

I’ve done a replacement spring before. It was relatively easy. But you need to 1) take the original broken spring to a machine shop or overheard door maker and ask them to make you a new one which is pretty much just wrapping a metal bar til it’s springy to the correct length using the correct gauge steel. 2) buy 2-3ft long metal rods that fit snugly in the crank holes. You need 2 of these. And 3) YouTube if you’re not feeling lucky enough to eye it.

Don’t over tighten or the door will pull itself up. Under tighten and the door will be heavy rendering the springs practically useless.

Crank one, insert 2nd shaft in. Crank insert next shaft. Let the bar do all the work. And stay out of the line of fire (that is if the bar were to slip, don’t be in front of where the bar would shoot out at you)

It was a fun project for me. And 10 years later I still have the metal rods I used. They’re holding up fence posts that are rotted out right now. Recycle. :)