That model had a "Learn" button that worked just like the newer SRT or Smart buttons for programming so you can use the information in the links below to reprogram the PIN code on the keyless entry.
If the opener is reluctant to accept a code then the memory may be full. You can reset the memory per the instructions in the second link below but you will then need to reprogram all the remotes and your keyless entry keypad.
Unfortunately, the owner's manual for that particular model is not currently available electronically through Manage My Home. But you can still order the manual through your Sears Store or Sears.com using the part number 09.139. 114A1140 to get more detailed information.