The mighty polymaker HT PLA rated for 150C showed promising results.  There was no melting in any of the trouble spots, after several cones.  It's more brittle & feels more like clay than normal PLA.  It prints at 230C while normal PLA clogs above 220C.   The 1kg roll is shorter than normal PLA because it's denser. The 1kg roll is  twice the price of the cheapest PLA.

The decision was made to try the 40mm diameter again with 2mm walls & no reinforcing structures.

The chopsticks got reprinted in HT PLA.  Not easy to get the cone in the narrower diameter but it looks much better.  HT PLA held up to the narrower diameter.

A caulking plug holds the engine section on instead of screws.