Did you check the power supply voltages and contacts?  The flickering display   
   suggests that the contacts might need to be cleaned.   
      
   If you boot into Model III ROM BASIC mode by holding the break key when   
   hitting reset, do you get a stable display?  If so, can you enter a simple   
   program to see if it works?  Something like   
      
   for j=1 to 1023: print j;: next   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)