I had bought several packs fo 100 over that past few years that were all perfect. The last one I bought, however,
had 9 duds in the bag that were broken apart. I sent them a note, and I got an envelope with replacements in the
mail a few weeks later.
I have never had any defective wobblers in FVM wheelsets. But I have had the ones noted above come completely
popped apart.
I have also had the problem mentioned earlier, when popping them into a sideframe. If you push on the
wheel that has the insulator, sometimes the plastic center will pop right out of the rim, and I have found it
almost impossible to ever get it pressed back on perfectly so that there is zero wobble to it, so I just discard
those. But I have since learned to never press on that side to avoid this problem.