Started putting the HH together tonight. One thing not previously tested were the PBDB (4) because I didn't have the pops themselves in place when I did an initial test of most things. Sure enough, four out of five don't work! The fifth is one I put in for the basement upkicker, and that's fine - it was a board I had, not in the game and subject to the corrosion issues dealt with elsewhere. The traces on them are corroded under the seal, and I suspect that's the issue as the components are all new. One doesn't work, one locks on when activated, and two just lock on immediately.
So chasing four clean boards (got the components to rebuild them if they need it). Happy to buy singly if any members have one or two pares.