You need to turn it off and remove plates,put in kitchen sink and spray with windex and dry with paper towels, now clean the bottom of the three plates too.
before you reinstall the plates look down inside you will see three thin lines of metal,make sure there is no lint or dust on them,reinstall and let set for five min. to allow any windex that might still be wet then turn on low for a couple of min.then go to medium