buldog5151bass
Kibble, milkbones, and P Basses. And redheads.
To the best of my knowledge, it's NOT that they "aren't working properly", it's that the seal/fit is not correct! Different issue!
That goes back to faulty impressions, and in @Joe Nerve's case.. they did not use a bite block when taking the impressions!
I suggested they get redone [with bite block] and send buds and new impressions to vendor for a refit!
Right, so then he wasn't fitted correctly.
My attitude is if something is custom, it better be right. I make custom baseball bats. If someone isn't happy because they didn't get what we discussed, I make it right.