Tektronix 4097 GPIB 8" Floppy Drive

Hello, all, I realize that this is likely a shot in the dark, but if there's any please that I might find some help, it's going to be here. There isn't much Tektronix information out there. I recently received a Tektronix 4051 in very nice shape, fully operational. Along with that, a slew of cartridge tapes, ROMPacks, two Joysticks, and a Tek 4907 8" Floppy Disc subsystem. The 4907 connects to the 4051 via GPIB, and there's a "File Manager" ROMPack that goes into a ROM Backpack slot to provide the code to the 4051 to drive the floppy system. The 4907 has a built in controller based on a Motorola 6800 CPU that handles the GPIB communications, running the floppy drive, and everything necessary to make the drive an intelligent peripheral. The 4907 is in nice shape...everything inside is very clean. Power supply voltages are all where they should be, with minimal ripple. The controller is a set of two boards. The bottom board, fairly large, contains the CPU, RAM, and all of the stuff for the GPIB interface and floppy drive interface. The top board, connected by a ribbon cable, appears to contain ROM that contains the 6800 code that runs the controller. Oddly, there is one chip missing in this top board, a socketed part. I don't know if it's *supposed* to be like this, or if perhaps a chip was perhaps scavenged from this position at some time. Identifying it will be a chore if it's a critical part. The RAM and ROM are all socketed, as well as a few other parts, so I made sure that all were securely in their sockets. I checked for any foreign debris on the circuit boards or elsewhere in the cabinet, and found nothing but one floppy disk write protect sticker. So, I powered it up. The device has four LEDs on the front panel. They are labeled BUSY, FAULT, FILE OPEN and CLOCK. When powered up, all the LEDs come on for a short time, then are turned off, then the CLOCK LED lights (this indicator lights to tell the user that the real-time (volatile) clock in the controller needs to be set to the date and time), then shortly (perhaps 1/2 second) thereafter, the FAULT light turns on. In reading the Operator's Manual (thank God for Bitsavers), it says that if the fault light comes on, it's an indication that there is a problem with the controller, and that if "restarting" does not clear it that the unit should be service by Tektronix factory service. Needless to say, getting Tektronix factory service to come look at this thing would be an exercise in futility. My guess is that either ROM checksum isn't passing checksum (Bad ROM? EEK, NO!!), or perhaps there's a RAM problem. Unfortunately, Bitsavers doesn't have the service manual, which would certainly make it easier to diagnose the problem. I'm looking for guidance in terms of trying to fix it. Anyone out there have a copy of the "4907 File Manager Service Manual" that they'd care to share (e.g., I'll borrow and scan and make available to Al), or scan it and send to me? I'll check the obvious...scope out the 6800 to make sure the address/data line are wiggling, and check for stuck levels on the address/data bus, but beyond that, without a Logic Analyzer or Emulator, it's going to be pretty difficult to proceed further. I'd love to get this drive working on the 4051, as it'd make it a lot easier to gather up all of the software that is on the batch of 1/4" cartridge tapes that came with the system, and then upload them somewhere, perhaps to the Bitsavers software archive.