I have a PEPSI MUSICAL SYRUP DISPENSER (I think it may be called a Tap Knob) that was attached to the syrup container and when you press the button to dispense syrup into a glass, it plays an old Pepsi advertising jingle. I have not seen another like it anywhere and can not find it in any collectable books. Can anyone give me some info on this item-what is it worth, where can I find it listed. Any help would be appreciated.