The only Delrin-to-metal assembly contact occurs where the small gear is mounted to the counter shaft. In the Model JR this will be a press fit. The hole in the gear will be undersized, and the gear will be pressed onto the shaft. We believe this will work - the 500 mile endurance test showed no tendency for the joint to loosen, and it takes quite a bit of prying to remove the gear from the shaft.
As a fallback position, we can always add a setscrew, but this will probably not be necessary.
The counter will attach to the gear drive with two small bolts. No glue will be used.