Does anyone know about 11/750 hardware ?

I have an 11/750 that will not boot. 

Upon startup the console terminal responds with a % sign. And that is 
all. I believe that the console should respond with
%
%%
some diags ...
>>>

I'm only getting halfway there. The memory and controller is all 
showing  theit green leds... I have tried with the UNIBUS connected 
and without.. no change. We have pulled the processor boards and 
cleaned the sockets of the dips and also cleaned the mating sockets 
in the comet bus.

Ideas ??

 

**************************************
* Dave Arthur                        *
* Business Instructor                *
*                                    *
* NSCC Burridge Campus               *
* Yarmouth, N.S.                     *
* ARTHUR_DAVE@burridge.nscc.ns.ca    *
**************************************