Japanese Type 97 Turn and Bank indicator need front knob dimensions

[Bobakman]

I recently acquired a Japanese WW2 era type 97 turn and bank indicator. This variant has the adjustable valve for controlling either the vacuum or air pressure to the instrument. Unfortunatly my instrument is missing the knob and the vent port cap. I am planning on 3D printing a replacement knob for display purposes and am asking here if any members have this same type instrument and can provide exact dimensions of the knob.
The instrument is currently on its way to me so I have not yet recieved it.
The photos are from the listing that I purchased it from and the photo of the knob was from a different source.
Any and all help will be much appreciated.
Regards, Bob

 

[Bobakman]

Well despite not having the dimensions plan "B" has worked. My Son was able to figure things out and we 3D printed the missig parts. Just need to sand the knob a bit to smooth out the lines that appear and paint them to match the gauges current look and it will be ready for display.
Bob