My two-car garage door opener lately does not open the door all the way. It only goes up about a foot or so and then stops. I am able to "help" it up if I press the button and then lift on it. It will open all the way when I do this. The unit will close the door no problem, it just seems weak when trying to open. I began to have this problem at the end of last winter and then once spring and the warmer weather hit, it did not have trouble opening so I thought I would fix it this year if it did it again when cold weather hit. Well, now that its is cooling off again, it just started doing this. WILL NOT OPEN more than a foot, but closes fine. I want to avoid a repair man. I am thinking I either need to replace the unit, or get new springs? Neither of the springs are broken currently. Any ideas??