Pawlowski6132: Thanks, just the same.
Jose Angel had the right assessment of the situation. On closer inspection, the cam is dedicated to a specific length lens. An Elwood catalog from the late 40's or early 50's may have shown optional cams available for alternative lens.
Adding a 4 inch extension to the threaded bolt (D) puts the 300mm lens in approximate range, and with the rack and pinion mechanism, I'm able to manually fine focus.
My sincere appreciation to those of you who offered help. Were anyone to run across an Elwood 8 x 10manual which discusses the autofocus, I'd like a copy:
thefarmme@prexar.com
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