Ben
It depends on how much scale you have. If it's just preventative maintenance... pretty easy.
Unplug the machine. Turn off the water.
remove the over pressure relief valve on top of the boiler. Dump 1/4 cup of citric acid in the tank
Put the pressure relief valve back on. Turn on water, plug in the machine and bring up to temp. Let sit for 1/2 hour.
Run the hot water and steam wands over and over until you think you have drained the boiler 3 or so times.
Then turn off the water, remove the cap on the top of each grouphead (there is a filter under the cap)... pour 1/8 tsp of citric acid in, replace the cap. Turn on the water and let sit for 1/2 hour.. run water through the group...
You can do both at the same time (groupheads and boiler). Make sure you run enough water that you can no longer taste the citric acid.
If its really bad.... disassemble everything and soak in a citric acid bath for 2 - 4 hours. Re-assemble and run lots of water through everything. This will require new gaskets and seals.
