From Phil McKnight on the CoffeeSnobs forums:
When the machine is returned to one of our service centers, it will be drained by removing the tubes supplying water to the 2 boilers, inserting small hoses into the boilers & sucking out the water.
Water inlet tubes will be replaced & the boilers filled with a de-scale solution via the water tank, left for the appropriate time, then the boilers drained the same way, re-filled & drained with fresh filtered water several times so there is no de-scale solution residue, then returned empty to the customer for use.
Its not a complicated process, but clearly one we cant endorse being done by a customer while the machine is under its 2 year warranty. Im sure after the warranty period is over, many on this forum would be capable of performing the de-scale themselves.
Looks like it's not too hard.
Some other bits:
Replacing the OPV with a brass one:
Adjusting the stock OPV: