Unless you know how to unload the tension on the torsion spring, this is not safe for you to do yourself. There are plenty of videos on the internet that show you how to do it, but be aware that the consequences ofusing the wrong tools or doing it wrong will likely result in serious injury, such as broken bones or amputated limbs, or death.
You should probably hire a pro to unload the torsion spring.
Any door should open easily by hand. It's a common misconception that garage doors are heavy and need motor drives to lift them. Nope. You don't have to lift the door at all. They have a spring mechanism which fully counter-balances the weight of the door, and the only resistance is rollers, hinges and gaskets. (I did some rehab on some rough old 12x16' industrial doors, mind you these doors probably weigh 300 pounds, and they all now open easily.)
When you work a door by hand, you feel the mechanism work. If it starts to resist or bind, you know it and are likely to fix it before it gets too bad.
So, motor drives are just a convenience. But there's a nasty side-effect: you don't feel the door, and the opener doesn't tell you - it forces the door anyway, which is the worst thing to do to a damaged door. It turns minor damage into more serious damage, until the door fails entirely.
So the answer is easy: Disconnect the motor drive and operate the door by hand. It should operate relatively easily. If it doesn't - repair the door. There's plenty of DIY information out there. Just beware of the spring mechanism, it contains a lot of energy and can hurt you.
I distrust the salesman's rap of "25 point inspection, conclusion need new door, and by amazing coincidence that's what I get paid commission on". Those Torquemaster springs can be obtained... and if I recall they have a pretty nice winding mechanism, which solves the scariest part of working with garage doors.
Best Answer
Depends if it is a swinging door (California) or a roll up door. The roll up has one spring that runs across the header. If you mess with this you are messing with death. It's that simple.
The California style that swings out has two springs on each side of the door. These springs can be changed as a DIY. Open the door, which will be very hard, and prop the door open. If you remove the what is propping the door it will slam very hard and maybe make you wish you were dead. There are many different types of springs so what you buy has to be an exact match. Changing it you takes nothing more than brawn. I've done a few over the years because they are used mostly on wood doors and these dry out and then absorb water and back and forth until they weigh almost twice their weight. The springs and openers start breaking from the extra weight.
To recap, if the torsion springs is above the door then leave it for a professional. The side springs can be done - video.