A local shop was telling a friend of mine how there were changes made to the selected sonic frequency of the ultrasonic generators. I think I remember reading that this took place during the initial engineering of the unit or in early production, but I hadn't heard or read anything since. Has anyone heard if there has been any change made to the sonic frequency used in the cleaning process? I bought mine in 2014 and I'd be interested in knowing if any changes have been made since then. I think my friend has been given incomplete or old info.