Warbird Information Exchange

So I recently purchased this O2A compass from an Antique Fair. As you can see it is mounted in some homemade contraption, made of PVC and Cork. Once I removed the rubber seal the little prongs holding it in place snapped off easily. This allowed me to remove the compass. I am certain that it is missing more than just the Azimuth. Can anyone tell me how much of it is missing, is it just an outer casing and Azimuth. Also does anyone have a spare outer casing or Azimuth or even tech manuals or drawings of this thing, any help would be great!
I am also on the look out for B 25 Mitchell wooden seat plans/ drawings and Sperry gyro spares (side unit)?

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Always in the market for P-39 or Beaufighter parts