Question on pulley bolted to dampner loosening up

That's strange. I've used the 5" Moroso aluminum pulley for many years on conventional Pioneer SFI steel balancers and never had an issue. In fact, I only used 3 of the 6 allen head screws to secure it because the pulley has an offset hole for pre-'72 balancers and the Pioneer has equal spacing. I just used every other one to maintain balance, skipping the offset.

Not trying to be a smart ***, but it could be the "harmonics" produced/allowed by that harmonic balancer!