[rootmatt]

Yeah. Mine was like that. The PO or dealer wedged a bit of paper under the dial to give some friction.
It is indeed adjusting the temp even when you feel no resistance. The resistance you feel as you get to zero is the dial hitting a switch that will finally turn the mongrel thing off. Trouble is: without friction, the dial won't stay there.
On inspection, I found that the dial was riding high on its stem. All I had to do was push the dial firmly down on its stem and the dial engage a detent arrangement that makes it click as it turns. Magic.
Hope yours is as easy.