If the steam wand or hot water tap is leaking slighty, the actuator pin might be stuck. This issue can be solved with lubricating the o-rings on the actuator pin.
Lubricating Actuator Pin
Using a large Flathead screw driver remove the actuator screw holding the hub and handle in place
Careful to keep all of the washers on the actuator screw in place when removing
Remove actuator and handle
Set the actuator hub aside
Locate the actuator pin and remove with pliers. Wrap the pliers in a towel as to not damage the pin.
If the leak stops, the pin is the cause and likely needs to be lubricated, If the valve still leaks, the internal needs to be rebuilt.
Using food safe lube, lube around the two o-rings and re install
Press the pin with your finger to check operation of the valve.