Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Many of us have collected several of Jin's smaller offerings in the Stirling Cycle engines line and found them to be amazing little machines that run surprisingly well given their diminutive proportions. However, I have noted that there are a few "gaps" in the cataloging system, and I wonder if those are just engines that I missed when they were available, or were never offered for sale, for whatever reason. Certainly, a current search still does not reveal them, even though it readily turns up all the cataloged engines that were seen on offer back in the day.

Specifically, I'm asking what ever became of, or if anyone has ever seen any of the following Microcosm models:

J04
J05

-or-

J06J

Those that I do know of consists of the series J01, J02, J03, the long J06 series starting with J06A and running thru J06I, then missing J06J and ending with J06K, then with the finale J07, so that the line-up looks like this:

J01
J02
J03

J07

&

J06A
J06B
J06C
J06D
J06E
J06F
J06G
J06H
J06I

J06K

Any background info on these "missing" engines, would be appreciated!
Curious minds want to know?!?!