Good news #1: I've got the prototype of the 3D-printed lever !
It's almost good: the radius of the round cover on the base of the lever must be increased a tiny little bit since it's scratching along the edges of the potentiometers. The dimensions of the lever itself are more or less identical to the Vectrex original part. After modification I'll try to get a few items printed.
Good news #2: I've got the tracking number of the ordered buttons right from Japan. They are coming...
Bad news #1: I discovered a weakness in the electronic design of my board, which is bad for the response of auto fire. For most games like "Minestorm", that's not a problem, where the finger presses the fire button more or less constantly. But there might be other games. I will modify the circuitry a bit, which is a lot of work and which doesn't make the boards look more beautiful. But I think functionality comes first.