Source for crown to fit a 40s cal 332 bumper 2583-4 case?

I've managed to lose the crown from my late 40s 332 cal bumper auto. No idea what happened, it's my everyday watch and only gets taken off at night, but the stem has sheared and the crown is nowhere to be seen.

I've been trying to find a replacement as per the original - this is the only photo I have showing the original crown. The case is a 2583-4 and the pipe is 2.5mm with a 1.75mm bore. I've yet to pop the stem out to measure but assuming it's 0.9mm tap 10.

If anyone can point me in the right direction with a part number so I get my old friend back on my wrist I'd appreciate it.

David