We have a Sears garage door opener model139651500, serial no E027950. The unit and door work fine from the push button, but the car remotes will not operate the door unless I go with 5 to 6 feet of the receiver in the garage and hold press the button. The batteries have been replaced and test like new in both units? What can we do to get range from within the car. Just bought the home with this opener and previous own said it worked well until a few months ago?