Number keys, 1 to 8, stopped working.

The number keys 1 to 8 on my MacBook Pro, have suddenly stopped working, for no reason.

My MacBook Pro is in otherwise perfect condition, and nothing has ever been spilled on it nor has it ever been dropped.

I've had my Mac for about 3 years.

The numbers 9 and 0 work, and every other key is perfect.

Since the problem occurred:

I have reset the NVRAM and PRAM.

I have pressed the option key 5 times.

I updated to OS X Mavericks.

I started up in safe mode with no differences.

I have taken off the keys and cleaned them.

I have left the laptop off for a few days.

Nothing so far has worked.

I have looked at the possibility of replacing my logic board as I am pretty sure my keyboard is fine.

I would like some advice on anything I might be able to do first before I decide to replace my logic board, as this is a bit drastic.