Problem with Gameboy Advance SP

So I bought the old man a Gameboy Advance SP for xmas actually off a member on this board not too long ago. The system was practically new, extremely mint and had no problems whatsoever for the first couple of months. Recently the A button has stopped working some of the time. Basically youll press the A button and it's like its dead. The button is not sticking or anything, it's like it's not making proper contact or something? When the problem happens it will usually go away after hitting the button again rapidly 4 or 5 times, but it always returns again later. Just wondering if anyone could give me a suggestion or let me know if this sounds like its an easy fix if i take the system apart. He does play the system daily and does beat it up a bit but his old gameboy and gameboy advance took beatings for years without any problems so this is surprising to me regardless. So basically it is either try to fix it or it looks like ill be shopping for a new system. I'd really appreciate any help or suggestions. Thanks...

buy a junk one with good buttons and switche em, should be to hard of a job.....