Thanks Dave. I'm not sure to what extend engineering extends to execution but there needed to be more work on ensuring positive fit before the moulds were made. The gas tank plug is a good idea but it's too small. To me, that looks like there was not enough testing, an indifferent attitude to the results of the test shots, or a reluctance to spend money adjusting moulds. Generally, fit is sloppy but I've had worse.
The wing issue is partly my doing in that I probably shaved off too much material to get the joint to fit but the gas tank plug and the rocker covers are all Airfix. I've not got to the undercart yet and Geo has warned me about it a couple of times. Right now, my worry is how to fit the damned ailerons which don't fit well even if the wing halves were properly aligned. With the misalignment, the issue is magnified.