Thanks curtismacc
I found an 80mm M8 threaded rod with a smaller knob that worked well without the leveler installed to secure the Sky Watcher shoe to the wedge. I was afraid that extending the body of the Seestar further from the wedge (with the leveler or some other kind of tripod spacer) would make toppling more likely. I installed an M6 x 1.0 nut on the thumb screw (on the Sky Watcher shoe). With the nut in place, the end of the thumb screw does not extend far enough to damage the base of the Seestar. Gordon
