-what is the thickness of your glass?
-do you have the motor side pad adjusted properly for your glass thickness? if you do adjust for a thicker glass thickness to create a little stronger magnet attraction.
-disassemble the powerhead side and check your bearing play. the manual for it tells how to check this play.
-within the powerhead side do you have the black spacer installed or the white/clear spacer?
how long have you been running it? one of mine took a week to quiet up and the other a month.
all else fails throw it out the window
