I purchased an S-470 a little over a year ago and am very pleased with the way it grills.  Its a quality grill that is easy to clean.  However, the knobs are complete trash.  The arbors on the knobs simply crack and break.  I am now on my third breakage.  WEBER, WHY AREN'T YOU RETROFITTING THESE KNOBS?  WHY ISN'T THERE A NEW SOLUTION?