Dell Latitude keyboard problems

I have a second hand Dell Latitude which I seem to be having some keyboard problems with. It seems to be with a line of keys 8IK, I used to be able to get them working by rebooting the laptop, but find that now I have to keep hitting the keys to get them to work, sometimes even this dosn't fix the problem, when I get them to work, they work find until the laptop is wtich ed off.