Well, I decided to go with my gut and deviate slightly from the order of the plans. I had so much trouble riveting on the counterweight assembly after the skin was riveted on, that I decided to rivet on the counterweight assembly and then do the skins. I put the 4 difficult rivets in without a problem, perfect heads, and then I started to rivet the top skin to the spar. So far, I think I made a good choice, but ask me in a few days.
