Do you have separate springs on each slide of the door right over the
opening? That is a torsion bar type of lifter and is for the pros.

I'm pretty sure I have torsion springs - mounted above the door (one
on either side of the center), parallel to the ground.

I'm not particularly timid in general - but I've had a big spring in a
heavy drafting table nearly take some fingers off once (those were not
torsion style springs).

If there is a simple way to adjust the tension on those types of
springs - say a bolt to tighten or loosen? I could easily do that.

Thanks.

-JJ

OK; that's the type system that's dangerous at best and could result in
a completely non-working assembly for the uniniated at worst. As
someone said, that's definitely a job for the pros. One slip of the
torsion adjustment puller bar and whoop! Everything unwinds very, very
quickly, and could cause a lot of collateral damage in the process.

If you get a pro in they'll not only have the right tools but will know
exactly how to do it safely. And, they'll do it quickly and usually get
it right the first time. This is also a case where you want to be sure
they carry their own insurance; you don't want injuries to be applied to
yours should anything go wrong.

Not to be a killjoy here, but one of the advantages of torsion springs
is the tension for the door is always balanced; it can't really get
wrong like separate springs along the track on each side can. And which
I thought it sounded like you had up until now, so whoever asked that
question was wise in asking it, AND in recommending you get a pro.
The problem is more likely to be either a wire has slipped in a
wirebolt, allowing one wire on one side to get longer than the other,
effectively putting all the "pull" power on one wire. At some point,
the tracks won't be perfectly aligned and they will allow the door to
cock in the rails.
Another possibility is the tracks themselves have been bumped or
somehow gotten out of alignment. By catching or putting uneven friction
on the door movement within the tracks, eventually the power of the
opener forces the door to cock or twist between the rails. A pro can
spot that in a hurry. And, it's the less likely of the possibilities, I
think.

I'm not a garage door expert; just an alley-hanger-arounder from Chgo
were we Hank Hill'd our own home repairs. Watched a guy do a torsion
spring once that twisted itself off the header (16' door) when he put
the bar in and gave it a good pull, and it bounced around the alley like
a rubber ball for a few seconds! The header was wet & rotted; lags just
pulled completely out, one at a time, with a loud "pop" for the last
three of them. No one got hurt, but a stepladder wasn't usable for
setpping on anymoreg. After the header was replaced, the torsion
system was bolted instead of lagged!

--
HTH

Twayne