Thanks Phil, as always.

I just heard from Yang JYan. Turns out that the board order is reversed of what I thought. As you look at it from the front:

SM2  SM1  SM0

Makes sense when you think about it. English and Europeans read left to right. Chinese read right to left. Both want to count up from 0.

Too bad it's not clearly documented anywhere.

So I didn't move the problem board. It might be a bad hash board after all, not the slot.

I'll move it in the next day or so, then see what happens.

Phil, no matter what happens, I'll send you some spare data bridge boards when this is done. I've got plenty ;-)