I've been playing with my new toy every day since Christmas. Figured out a few things.
First of all, the plastic bushings in the rocker arm were a pain in the neck, because there was no way to tighten the pivot screws properly without deforming the bushings and making the pivots bind up. Fortunately, there were identical brass bushings available for a different model, and they work splendidly. As a side benefit, I can oil them, though I have to be careful about applying too much oil -- the reciprocating motion will shake loose any excess, and the top piston REALLY doesn't like being contaminated with oil.
Nano Oil works way better than 3-in-1. I expected it would, but the amount of difference is remarkable. The engine speeds up immediately instead of needing to heat up to thin-out the oil first.
The top piston is a strange creature. It has a large surface area that can scuff against the brass cylinder, so minimizing friction is of paramount importance, but at the same time any
liquid lubrication will cause massive drag and prevent the engine from speeding up beyond idle. The German company that makes the engine actually recommends a dry ceramic paste, smeared on so thin as to be transparent but slightly hazy in appearance. Boy, that stuff works great, whatever it is. I wouldn't use it on anything I can use liquid lubrication on, but it's completely stopped the appearance of wear on the cylinder walls, and it doesn't drag at all, so the engine runs like gangbusters.
If anyone wants to play with the ceramic paste, to see if it's useful in other applications, I got it here:
http://www.ministeam.com/acatalog/Boehm_Parts.html It comes in a little plastic syringe and it's EXTREMELY difficult to squeeze out, but only a tiny bit is necessary so it's not a huge problem.