The Steam function requires 2 things:
# The 2nd stage heater element heats the water to the higher temperature
# The Steam valve be opened and clear
The heating stage is a function of the electrical elements - the switch, the thermostat, and the heater element - they must be working properly in order to heat the water.
The Steam wand only requires that the Steam valve be working properly, and the wand be free of obstruction.
'''Troubleshooting:''' the steam valve has a small locking screw that can become loosened and then it will fail to operate the internal valve when the knob is turned. Or the valve can become corroded internally. Either of those conditions could cause the steam to fail or not flow fully.