Happened in my family a number of years ago. The instructions said to crank the spring 7 1/4 turns. So it was really make a 1/4 turn, repeat 7 times. Not 7 full turns plus 1/4 additional.
After pulling the vice grips off, the door shot up with such force that it knocked the ladder over, causing a broken collar bone in the process.
I tried and failed to repair before, but didn't get injured. I had to take great care with the vice grips and other implements I was using; my intuition was they could become missiles.
After pulling the vice grips off, the door shot up with such force that it knocked the ladder over, causing a broken collar bone in the process.