Shed - Getting the perfect shed on my Jane Loom

Question: I have a Jane 70 on a stand, and it seems I am always tweaking the shaft height to figure out where is the best shed.  How big should the shed be on a Jane loom, and how high should the shafts be set at rest?  I note that my floating selvedges are not in the centre of my shed, and wonder if I have the shafts set too high.  When the shafts are down there is about 1/2 inch between the bottom of the shaft and the elastic cords.

Below is the picture of my shed on the Jane Loom.

My shafts sit lower than yours. They are pretty much just above the elastics. Below is a picture of what my shafts look like at the bottom.

When I put a ruler on the top of the shafts it is approx. 9 1/2” to the top of the castle.