It’s likely the CA3094 in the oscillator has quit. It’s a common problem. They’re about $5 each at Small Bear.
Hi The EH Man, my small stone V1, pot date 1377552 has the same symptoms, no phase sound. Could you please tell me which IC shall I replace? A1, A2, A3, A4, A5 or A6? see the Small Stone V1 schematic