Water is leaking from the steam wand whenever the machine is on regardless of the mode the machine is in. There will be a stream of water out of the wand even if the machine is just in the "heat water" mode. I suspect the steam control knob is faulty because it doesn't turn smoothly, but I'm not sure how to confirm this. The knob is in the closed position. I have recently descaled the machine. Is there a way to confirm that the knob is the issue? Is there anything else I should check? The frother? If it is the knob, I've seen that I can order a replacement, but I'm not sure how to remove it from the core.