need HP 9121D cabinet/circuit board

I've got a 9121D floppy subsystem that fails to pass POST. Drives wink on power up, fan turns, fuses check out ok, but indicator LED on circuit board never comes on and drives remain invisible to IB controller (1630G logic analyzer). I've blown out the dust, reseated cables and the one socketed PROM and that's all I can figure out to do. Nothing seems obviously damaged or smoked. I didn't have the unit a couple of months ago when people were tossing these things into dumpsters, but hopefully someone still has a known (or possibly) good cabinet/circuit board sitting on the shelf at some reasonable price. I guess I'd also consider buying another complete subsystem if necessary. Obviously, service data or trouble-shooting ideas would be welcome Thanks. Jack Rubin Wilmette, Illinois USA