I have difficulty with the floating selvedge; I know it is not threaded through a heddle but through the reed. When I’m weaving, though, it is always on the lower edge. I am using a table loom at the moment, but even with a jack loom I still experience this problem. Am I supposed to have to lift the floating selvedge when weaving?
I’m thinking the problem is that the down shed on both your looms is not far enough down (a common issue with light-weight rising-shed looms) so that the floating selvedge is too close to the bottom of the shed. You need to do something to raise the floating selvedges to the middle of the shed. You could put a block under them on each side (with a C-clamp on the back beam) or loop a cord from the castle on each side around the floating selvedge to raise it.