No requirement
AFAIK. Like I said - I periodically list mine so I can keep track. I was on par to have about 60 engines, but I just gave 4 to a friend of mine.
Im trying to find socket head screws to replace the JIS screws in several of my older Enya engines and one OS engine. Anyone got any insight where to find screws with a major diameter of 2.75mm at .60mm pitch in 6.7mm and 22.7mm lengths? It seems the 12-32 prop nut is a little easier to find, but I'm at a loss on all of it currently. The Enya screws are 2.90mm at .60 pitch and 7.5mm long.