Bump. Just added a link on original post pointing to a recent ts.com thread about the thread size/pitch of the knob on a genuine Windtech clamp.
I recently shattered the plastic knob that secures the 5/8"-27 stud during an FOB situation where I had the Windtech clamped to a stand, minus mics (thank, God). The stand smacked pavement and destroyed the round, plastic knob.