If you have some calipers and can measure the depth of the peg hole in mm, I can tell you whether it's the same as my copy. The tolerances on Shapeways prints aren't perfect, but it looks off by more than I'd expect in your pic. Even if the width is correct, my guess is still that there's some compacted loose material in the hole getting in your way. If you use a narrow, hard scraping utensil (like a hobby knife, eyeglasses-sized flathead screwdriver or maybe icepick) you should be able to carve some more depth out of the peg hole if you work at it. I've had to do that for a few of the other helmets I've bought, but not by as much as yours seems to be.