It should be at max C now with the plates meshed?
doesn't it go back in reverse as you put the black cone on, then screw the driver in, the drive thrust washer meets the front of the cone and it starts pulling the brass cylindrical thing out, though the pin in the cone must fit into the hole of the brass cylinder so that it can not rotate. ?
and at some point it is back at min capacitance?
It all goes back together and appears to operate normally. There’s no anti-rotation feature in that the pin/threaded rod in the cone doesn’t touch the brass bit until it’s at or near minimum capacitance. If you rotate the cone the pin either hits the top of the brass thing or goes inside a shallow hole then hits it. But you can see daylight between the fixed and moving plates before it bottoms in the hole.
There doesn’t seem to be anything missing. I’ve zero prior hands on time with vacuum caps; it just seems like the max capacity has been reached point shouldn’t be indicated by the thing coming apart….
Would I be crazy to put a little epoxy on it? Or something else?
At least in my usage it will never be near the maximum. It’s a 700pF cap being used as the tune/input side of the pi network; it may never even be half meshed.
Ed