Softlighter II Mechanical Question

Anybody know what thread is on the umbrella shaft extension of my new 46" Photek Softlighter II with 8mm shaft?

I'm using the Softlighter II with an Alien Bee 800, and am concerned about deforming the female thread in the umbrella shaft by overtightening the AB umbrella clamp.  If I knew the thread size I might be able to find a screw to insert as a reinforcement after removing the shaft extension and before tightening the clamp.  It seems to be a very fine thread.

Is the possibility of deforming the hollow umbrella-shaft  even an issue?

TIA

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JerryG
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