CMD CQD-220TM problems

Here's a quandary that I've posted a few places, with varying success. ?I have a CMD CQD-220TM SCSI board (QBUS MSCP SCSI, drive and tape) which was working fine when I got it. ?It's now only partially functional with a few odd symptoms on my 11/23+. I'm honestly puzzled by this; it was working fine when I got it, and then I plugged it in after a move and no dice. ?I'm still banging on it with IDA pro. ?I hope it's not a busted PAL/GAL/PLA (of which there are about 20 on the board), because for the most part there's no way of redoing any of those without spending weeks on the assembly trying to figure out what they're supposed to do. ?The SCSI chip (a 53C90A) is a socketed PLCC, and they're not impossible to find second-hand, so if it turns out to be a problem there, I should be able to fix that by just throwing some money at it.