The FM mod for Cocoquantus is done by adding five input screws, each wired to a ready-to-wire CV input pad on one of the quantussy oscillators. I arranged the screws in an arc, following a photo I saw. There is plenty of room, but be careful with placement to clear everything below deck. The left-most screw on mine comes very close to the nearby input jack. It’s a simple mod for anyone with soldering experience. The new CV input is sensitive and sweeps the oscillator over a very wide range when patched directly to one of the triangle wave outputs. Sometimes I patch in a potentiometer with alligator clips to attenuate the CV.
I could not find an exact match for the screws at two local hardware stores. The originals must be #4 brass wood screws, 3/4″ in length. The stores only had shorter #4s. The 3/4″ length ones were #6, so that’s what I used. I managed to fit #4 flat washers under them.
White wires run from the screws to pads surrounded by white squares. The pads are easily identifiable, since these are the only ones inside a white square. Two of these are visible in the photo.