As I was going over my last entry (below) regarding my right-angle bug, I realized one of the differences I missed — how the dot contact is connected in the key circuit.
On the Codemaster and Simplex Auto bugs, the long spring steel assembly that has the actual dot contact attached to it is “hot”. On both of those keys, you'll see that the post (at the far left front of the key base) is insulated from the base. The adjustment — the post and screw midway between the left contact post and the contact end of the spring steel assembly — has rubber bumpers to insulate the adjustment from the base.
On my right-angle bug, the dot spring assembly and the keying lever are both at ground potential. Only the contact posts are “hot.”
This is a major difference, and explains why the key adjusts differently. In order to make the key operate like the Simplex Auto, it would require insulating the mounting post at far left from ground, and making it the dot contact rather than the dot contact post as situated on my key. Talk about reworking a key!
I had not done side-by-side comparisons until I posted the photos below, and that was when the difference was clear to me. Hmmmm….