Andy at the most excellent layout and resource blog Vero & Point-2-Point Layouts traced this interesting tonebender variant a few months ago. It is a tweaked Tonebender Mk. III/IV with an input cap blend control and a Big Muff tonestack with odd values. Schematic and tracing jornal is avaiable HERE.
*EDIT 220429* Andy discovered a mistake in the trace regarding the function of the Balance control. Layout is updated. LINK
