The wing fuel tanks need to be "expanded" to properly fit the fuel fill neck and caps. This is generally done prior to wing assembly, but RANS apparently did not do this work.
The task basically involves sealing all the wing tank fittings, then filling the tank with fuel, putting it in a warm place (out in the sun) and allowing the vapor pressure generated by the fuel to expand the tank to it's full size.
This involved building a couple of oversized padded saw horses to fit the wings, moving the wings outside, finding all the bits and pieces need to seal all the tank fittings up, filling the tank and waiting a week or so.
