Wow. You folks were spot-on ! The PM #13 ran great and full time till the fuel burned out.
I modified the application of the graphite to the power piston by simply dipping a small paintbrush in denatured alcohol , wet the piston with it, and then sprinkled the powdered graphite on to the wet piston.
I also notice a slight binding in the steel piston pin on the brass connecting rod. I lightly polished the piston pin with OOO steel wool, then gentle hollowed the connecting rod bearing hole very minutely with a small round file.