Assembled the centre section, quite simple to do.

On presentation of the centre section to the wing, the middle mark of the centre section was off the spar joint line by about 2mm (just over 1/16"). I checked the wing with a tape measure and confirmed that the spar joint was the actual centre - which it was.

What was causing the discrepancy was the half rib on the wing being at an angle relative to the centre section half rib. I cut loose the wing half rib from the dihedral brace and positioned the centre section lined up with the spar joint and epoxied all in place. Looks good.

Next top sheeting.