Francis X1 leaks water from steam valve when valve...

Question

My Francis X1 Has made hundreds of fabulous lattes (3 -4 per day) but for the second time has slowly developed a "leak" from the steam valve. Whenever the machine is turned on it drips and spurts out the valve even though the steam valve k**b is fully off. The problem is progressively getting worse and about 2 oz. of water is lost for each shot of espresso brewed. This same thing happened about 2 years ago and I sent the machine (directly) to the repair facility in Southern OR. I descale regularly and the repair facility told me I did not have a scale problem when it was fixed before, although they declined to say exactly what the problem had been. I really don't want to spend a couple hundred dollars to ship the machine and have it repaired again, but mostly I don't want to be without my machine. Any ideas?