FWIW, when I was having jello problems, I bought a Dubro truspin to balance my phantom's props. All 8 of them balanced perfectly, there was just nothing I could do to improve them.
I'm all for balancing props, but if my sample is at all representative, I suspect many with less-than-perfect (magnetic) balancers or alu rods being balanced on a drinking glass, will actually end up unbalancing their props.
Also, we've seen cracked shells on brand new phantoms, that havent even flown yet. So its more likely the root cause is either a manufacturing defect, or an issue with assembly, like overtightening certain screws or bolts, or bending the shell too much when putting it together.