I have a Napco GEM-RP8 home alarm keypad that does not consistently accept my codes when number keys are punched. The familiar "chirp" when punching keys fluctuate from weak to non- existent. It has become very difficult to set my home alarm. The keys affected seem to be the ones I use to enter my code. I tried blowing compressed air into keypad. At this point, does the keypad need to be replaced? Can I do this myself and can I replace the keypad with an updated model while I'm at it?