Some of the dials have a set screw - if the dial froze up due to dried up oil the set screw will no longer hold it - then it will just turn. To fix it you will have to remove the dial and grind out a flat spot on the shaft and then put the dial back on. But if you haven't taken care of the shaft not turning you will still have a problem. Look up the bottom inside the machine to where the dial is and put a couple drops of oil in there. Frozen knobs drive me nutty. Some times they can take a while to get to move.