Keyboard with pattern of some keys not working

[technoid]

Hey all, not sure where to post this. I have a generic PC/AT 101 keyboard where all the keys work except for the following... 6, 7, y, u, h, j, n, m. If you look at their physical position on keyboard, it looks like this:

 6 7
  y u
   h j
    n m

So it's like something is going on vertically. Could this be an electronic issue (dead resistor, cap, diode, etc, or bad controller chip, etc) rather than mechanical issue (cracked pcb & traces, etc)? This happened maybe nearly a decade ago & just finally decided to look into it. I don't think the keyboard ever fell off the desk & hit the floor, it just all of a sudden happened while using it, iirc. Anyone know what's going on, before I break it open?

 

[Chuck(G)]

A lot of the generic keyboards use a clear sheet that's been silver-printed with contacts. If one of the traces opens, you'll get the pattern of non-working keys. That can be repaired with a silver trace repair pen. See this video