If it were me, I would continue to repeat your test over the next few days to see it the results are reproducible. One other note I might add. My first job out of college was to help design a replacement product for one that had a very high failure rate. Our marketing department complained that it was guaranteed to fail within the warranty period. Studies showed that one of the main reasons for the high failure rate was the plug in boards even though both boards and connectors used gold plated contacts. Contamination caused the failures. Since the VFO gets its +6VDC and the Clarifier input mostly from PB1314, I suggest you pull it and use a pencil eraser to scrub its contacts as a precaution. Those results are getting very close to mine.