Another Friend for my Sagan Delay (Pedal PCB Caesar Chorus)

[RDL68]

"I've built a lot of BBD pedals and the scope biasing has been very reliable for me.  This one was weird.  The bias point (by ear) is towards the middle of the trimmer and there's only a narrow range that will produce chorusing. But the output from the BBD looks like more like an EKG than what I normally see.  Because it is chorusing in the middle of the trim, I don't think adjusting resistors values would resolve the issue.  I've had other BBDs that biased at the end of the trim rotation and those needed a resistor change.  Anyway, it works real good  So, maybe I'll let this this one slide."

Exactly, many builds & I've never seen this mystery surface before. Mine was just for myself so I let it go. If it was built to be sold I'm sure it would give me niggling thoughts, so I'd investigate until I nailed it & if that wasn't possible I'd rebuild the whole thing first (if it happened a 2nd time, gawd help me, hehe). These 2 builds of ours that it happened to are different circuits too, so it puzzles me whether it was something identical causing it (like something common wired off the pcb itself for eg) or 2 completely different things causing it. Mysteries without answers...