all you need is :
a soldering iron
a few micro switches
a screw driver
Step 1: OPEN THE PROCESOR
Step 2: GENTLY REMOVING THE FOOT SWITCHES PART
Step 3: SOLDERING THE NEW SWITCHES
for the bank buttons move on to the next step
Step 4: CHANGING THE BANK/ EFFECT TYPE BUTTONS
Step 5: GETTING TO THE PCB
one you get to the actual circuitry, remove the two screws and turn the cover and remove the knob buttons by just pulling them out. remove the nut and then you can remove the defected buttons and replace them.
Step 6: GETTING IT FINISHED
please excuse me if i made any expression mistakes and if i'm unclear in any of the steps; it's my first instructable.