So I wonder what happens if one of the MISB sets I have is missing a part? I am not ready to open any yet due to lack of time.
If a hat is missing they will send you an entire new box, just that simple. You just have to honestly answer these 3 questions:
1) What is missing? (a hat)
2) Is a hat missing? (yes...)
3) Is a hat REALLY missing? (yes...

)
(Ok, you will receive your new box in the mail in 6-10 business days...)
Cheers,
HDL
PS: This is fiction! Stunt performed by a professional, do not attempt to try at home!