Not too long ago, I wondered if I could add a chorus/vibrato selector switch to the Touchstone (Small Clone). Mr. Bean said all I needed to do was lift R6 for vibrato mode, so I rebuilt my enclosure with a spot for a switch and it turned out great! Excellent warbel.
Removed R6 (22k) and ran wires from its pads to the center of the DPDT ON-ON that I positioned between the pots. The chorus side of the switch has the 22k resistor, the vibrato side is empty - breaking the clean tone side of the circuit.