I've been having an extremely frustrating time trying to program a remote. The model number on the 1/2 HP GDO is 13953638SRT, I have one remote that works fine but need another one. The remote I have that works fine is grey with blue buttons. I purchased the exact same remote from with the same serial numbers on the back (security +) but the motor unit would not program it. The motor unit has a green LED light, next to the learn button and I followed the instructions to program to the letter. Next I tried a billion code remote (gray with gray buttons). Same results. Finally I tried a universal remote. Nothing. Then I decided to try to clear the memory by pushing the learn button for 6 seconds. It doesn't even erase the memory, (old remote still works) and it still wont program a new one.. I'm beginning to thinki I need to change the entire unit. Any suggestions?????