I bought 3 now in the past 5 months and you know what, they same thing happens everytime. The knobs have some sort of defect and they are impossible to fix. DO NOT BUY THIS ITEM, SPEND A LITTLE MORE AND GET A GOOD ONE THAT WILL LAST, I WISH I WAS SMART ENOUGH AFTER THE FIRST 2 BROKE!I just thought they kids were being rough.