The forward spinner bulkhead, when mounted has no access from the outside. Accordingly, locating the screw holes on the spinner is a head-scratcher. Plane geometry to the rescue! Using a shop-built compass, and with the spinner removed from the prop. hub, I triangulated the locations, based on the previously-drilled mounting holes at the rear bulkhead. Sixty years later, I'm so glad I paid attention in Mr. Bryant's class!