1. Its not a freewheel problem. In super slow pedaling I can clearly see the chain engage the tooth on the 36 ring, and then chatter on each tooth as the chain seats on the ring.
2. the drivetrain operates smoothly when in 36-19 mode, even though the chain is more slack in this combination, so slackness is not the cause. And the 36 ring is not on backwards.
3. The shifting is fine between the 36 and 52- 16 tooth difference is not a problem.
4. The chain is not rubbing on the front derailleur
5. The frame is not out of alignment, everything works perfectly when the 42 is on

So I'm thinking maybe the 36 ring is cut for modern, thinner chains and what is happening is my older, thicker chain is a few thousands too large in some dimension and maybe what I should do is replace it.
Just a guess.