Have you tried the test switch on A9? You should get two rows of capital A's, a square wave, and two more rows of A's at the bottom.? This "isolates the Processor Ram and the Processor I/O Bus from the Display Section." (I'm quoting the Service Manual here).? It won't give you a smoking gun but will rule out some areas.
Don't feel bad, I was ignored the first time I asked a question about a fixer upper 3582A I bought too.? Got it working finally though. :)
Dave
