I also have the same problem and am not sure what to do. The contractor who installed the faucets has been out twice to "fix" the problem, but afer a few weeks, the middle knob is stuck again! I have not tried to fix the problem myself and wonder if this is something I need to call someone in for?

By "same problem" do you mean that you have a Moen faucet or another brand? If another brand then what's its name.Please give us more details. Have you loosened the bonnet packing nut, ( the nut on the stem) a tad? Regards, Tom