Here is a board, including U12 transfer and postage, for US$70:
http://www.hdd-parts.com/20091021.htmlThe TVS diodes are D6 and D5, and the zero-ohm resistors are R82 and R81.
Q8 is the +3.3V pass transistor. Its voltages will be +3.9V, +5.0V, and +3.3V (BCE, left to right).
You should find +5V and -5V at the pin 1 end of the preamp connector (J1). These are the preamp's supply voltages.
You should also test the voltages at D4, D3, L1, and L2 near the SMOOTH motor controller. These are the two switchmode DC-DC converters. One supplies the Vcore voltage for the MCU (+1.35V ?), and the other supplies the -5V for the preamp.