With one cable on & the other off or broke you won't be able to get the
door to stay level again without fixing the cable or removing tension
on the spring (I don't recommend that you mess w/ the springs). Forcing
the door open may damage the track & the door could literally fall unto
you or the car which would not be a good thing. You should really leave
the door in whatever position it is in until it is repaired. It will be
faster & therefore cheaper for someone to fix.
Doordoc
www.DoorsAndOpeners.com