I recently had to change the gears in my Sears GDO because the original gear was stripped to a pile of dust. It worked fine for about 6 weeks when it started acting up again. When I pulled the cover off, the new gear was already stripping just like the original one which took at least 7 years to strip. Any thoughts?? I first thought of the springs, but the door does not seem to be too hard to lift as if the springs were weakening....