The drive in my Tandy Model 6000 has +5, +12 and +24 connected to it (pins 5, 4, and 1). The schematic in the service manual I have shows 4 as NC and a 7812 providing the 12v from the 24v line. The specs for the drive in the service manual do not mention +12 on pin 4 at all. The scematic at bitsavers isn't a lot of help. I don't have the drive here in front of me. Does anyone have one where they can verify the connections from the AMP power connector to see if pin 4 actually goes anywhere on theirs?