As the jig has to be moved frequently, I devised a system of leveling fore to aft with a water level and a tightly stretched steel wire. I added some dye to the water in the vinyl tube to visually assist this process. The wire serves as the center line and base line for all the station frames.

 

The steel wire is usually used in jewelry making, specifically for necklaces and bracelets. It is .019" diameter with 49 stainless steel stands coated in nylon. A 30 foot spool was $14 at the local bead store.