Same problem but not sure the reply to Yana will suffice. My unit is a 1/2 hp, model # 139.53646SRT1. There is a green button on the back of my unit. There is a geen LED light next to the green button. If you mash the green button once, the LED light comes on. I then attempted to input a new code (a 4 number code) and mashed the green button once. No such luck. I tried the same procedure by mashing and holding the green button until the LED light went back off (approx. 6 seconds). I then tried to set a new code (the same 4 digit number) and mash the green button. No dice. Can you supply a solution?