Calypso,

As far as I remember you have to unmount the keyboardunit (keys) by removing 8 or 10 screws in the bottom part of the X1.
Than remove the screws from the PCB with the contacts underneath the keyboard.
The strips have 2 contacts for each key. The time difference between closing is used for calculating the key-velocity value.

You forgot to answer my question about the 2 key failures ... did they occur at the same moments?