Microwave Touch Pad not Working

Few buttons (2, 5, 8 and vent fan) on my GE Microwave touchpad purchased on 2007 are not working. The model number is JVM1750DM1WW. I am not sure if it is the touch pad or the smart board issue. Should I replace both or one? Has anybody seen this problem or has any recommendations on where can I get the parts with less price?