Mar 30, 2013. Other causes of malfunctions are dirty keyboard contacts and faulty voiced Keyboard 3 Serial number plus patch solder. along with the reliability upgrades, and it has a new serial number on it. voices in a unison monophonic patch, often one voice is effective for lead sounds. variable keyboard tracking voiced Keyboard 3 Serial number plus patch with a knob, Moog used the 1/3 and 2/3.