Well, as many of you suspected, it was a small piece of the O-ring seal from the original filter that must have broke off and was stuck in the valve body. 
I now have a completely cleaned valve body, new fluid and filter, correctly adjusted and fully operable Overdrive.
Merry Christmas to me!
 
  
  
  
  
 
	
		
			
		
		
	
				
			I now have a completely cleaned valve body, new fluid and filter, correctly adjusted and fully operable Overdrive.
Merry Christmas to me!
 
  
  
  
  
 
 
 
		 
 
		