I noticed a problem with my craftsman GDO, model # 139.5399011 (~ 3 yrs old). I am trying to program an additional remote. When pressing the learn button on the motor unit, the yellow LED above the button is supposed to light up for 30 sec, allowing the additional remote to be programmed. This however is not happening. The LED lights up under other circumstances and the GDO works properly via the wall switch, the outside key pad and other, previously programmed remotes. Curiously, this problem affects both of my (identical) GDO units. Also, I am unable to reset codes as depressing the learn button for 6 seconds (or longer) does nothing. Any help would be much appreciated.