Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
If you think the keypad is going bad, you are probably right. If some keys produce a tone or a beep, all of the number keys should. That some do not, means your code did not work because some of it was not entered, some digits of it (the ones that did not beep) did not even 'register'.
To enter your code, or try to, again, absolutely lean on the keys that haven't beeped... without ripping the keypad off the wall, you can still apply a fair amount of force to a system that is already partially 'broken'. Maybe you can enter your code and clear the alarm and strobe and so forth for now, by that means.
And after that: replacing keypads is routine enough. Some brands have replacement key elements, but that's not true of Ademco keypads usually that I know of. So replacing the whole keypad will be the likely cure for the problem with some numbers not registering.
As for how likely that is: with a system that is 6 years old at minimum, and possibly twice as old, the keypad is very likely getting too old to limp along any more. Replacement of a defective keypad at that age is quite likely enough to be needed.
So in sum: keypad needs replacing, getting a tech out there might be a good way to go.
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