Well I stripped the paint off the ARR F7. The rivot strips reappeared on the left side. I reformulated the yellow to better match the decals and took extra care repainting the engine. This time, the paint was only about 2/3 the thickness of the last attempt.
Lo-and-behold the left side rivot strips disappeared again. The strips are much shallower then on the right side. Even with a think cote of paint they dissapear.
So mny question now is, for those who own IMRC F7s, does your model have this same defect?