[Test-Equipment] Tektronix 2236A Oscilloscope error message

[W1GOR]

Tektronix 2236A Scope. 

On the DMM readout, a flashing message "FAIL - ro" appears at power-up.

Can anyone tell me what this error message means..?   

I've tried calling the Tek service people, but no one knows what the message means.  The instrument was de-listed for service in 1999 by Tektronix, and they have no archives (quote: Tek Service Desk).  

Any advice is appreciated...

Thanks, Larry - W1GOR