[cctalk] TU58 troubleshooting

So I'm working on repairing a TU58 Dectape II drive. So far I have cleaned it up, replaced the rollers, put new bands in some TU58 carts, and have fixed the power supply so +5 and +12 are up and running. Turning on the unit with nothing in it results in a quick flash of light from the LED on the main board. Hooking it up to an 11/23+ and trying to boot off it gives me ERR 12 NON-EXISTENT CONTROLLER Drat. It's connected to the 11/23+ with a normal 10 pin ribbon cable with keys at both ends. So questions: Baud rates are wired in at 9600/9600 on both the unit and the CPU. 1) Is the quick flash on the inside LED normal when powered up 2) Does it require something more than a simple ribbon cable to connect to the CPU? 3) Should the unit do something else with a tape in and powered on? Thanks! Chris