Excerpted from http://tinyurl.com/djxdc5.Measure out exactly 10 ounces of room temperature water into your frothing pitcher and insert your frothing thermometer. Remove any frothing assist devices as you will need to use the bare wand.
Click on the steam switch and wait for the red "ready light" to come on.
Start steaming by opening up the black steam knob. You will notice the red light will go off after a short time indicating that the boiler heating elements are on and are actively heating the water. Keep steaming until the temperature light comes back on. Record the temperature. If it is not at least 140F (60C), your steam thermostat is running too cool and should be replaced.
The steam thermostat is very easy to replace and if you can wield a screwdriver, you can replace it yourself in a couple of minutes [keeping the usual precautions about working on electrical equipment in mind]. If you are replacing a thermostat, always remember to hand tighten only. Never use a wrench to tighten a thermostat on this machine.
When I replace a steam thermostat I always use a 155C or 165C model instead of the OEM 145C one.
