I had much the same problem. One faucet was fine; the other a very slow drip that you could turn off if you really forced the handle back. Here is what worked for me. I noticed that on the good faucet, the handle assembly was a little further up, and therefore had plenty of room to close. The handle is connected to that little ball thing in the spout with a screw thread. Rotate the handle while you hold the ball with something so as to extend the handle up a few turns. Then screw the whole handle assembly back down, making sure the plastic thing is orientated correctly (as Ischiavo send in the prior post).