I have a 15 yr old 1/2 hp craftsman gdo that works great, except it loses its memory for my garage door openers. The button on the wall will blink and I have to hit the green button on the back of the opener, hit one of the openers and it resets the opener. This may work for a day, week, month. I live in the flight path of an airport if that makes any difference. I have changed the codes on the remotes and opener to try and get away from frequencies that may be affecting it. Any ideas on what could be causing this?

Thanks.