ON MODIFICATIONS: As alluded to in the pamphlet, there are a few pads on the board that allow you to make some modifications to the synth. First, in the top left, you will see three pads labeled ABC and then three more labeled "OUTS." If you disable the solder jumper beneath these, this disconnects the three LFOs (the oscillators whose activity is indicated by the LEDs ) from the frequency divider. Each oscillators output is available at the pins labeled "OUT." The pins labeled ABC are the inputs to the frequency divider. By disconnecting the solder jumpers, you can use the LFOs externally, or run external signals into the ABC inputs (or add switches engage/disengage the LFOs).
In a similar fashion, in the circle at the bottom center, you can grab the main oscillator PRE-Frequency Divider at the pin labeled OUT, and access the input of the frequency divider at the pin labeled IN. If you disable the solder jumper on the back, you can use the raw oscillator externally and/or run external signals into the frequency divider (you will have to boost levels of this signal in order for it to trigger. Line level audio will not work).
Finally, if you don't like the sync oscillator, you can disable it by disconnecting the solder jumper circled on the left.