The people answering apparently don't know that you can use counter-weights, cables and pulleys instead of a torsion spring. It takes more space, but it rock solid and safer to fix.
Counterweights provide a constant force, whereas springs can be precisely balanced to the decreasing weight as the overhead door becomes more horizontal. It is inherently related to the design of segmented overhead doors.
300lbs of counterweights strapped to the doors would take up a good bit of space. Pulley systems would need to either be 1 to 1 or would need some space to fall below the garage floor or to be stored above garage door height.
They seem far safer, longer lasting, and cheaper and easier to repair than springs, but are more expensive to install, take up more space, and probably cost more all in all compared to springs.
You know, that design makes a lot of sense, since the door would be mostly horizontal by the time the pulley got close to bottoming out the motor would still be able to move it.
I bet those tubes go below the foundation though and god help you if the cable breaks and you have to fish those weights out to reattach it.
Maybe there is some easily reachable latch point on top or some sort of fluid pump port that will make it easier on you?
It is very common in some other countries.