word to the wise for anyone working on these monitors: before you unplug anything, make unique lines across the plug onto the headers so you know where the plugs go. one of the 3 pin headers if I'm not mistaken has B+ voltage running to it and it looks exactly like a 3 pin negative sync header -- you will destroy things if you hook this up wrong.
in fact @Jeffb707 if you could take an overhead picture of the deflection board to the best of your ability getting all the plugs in it, that would be majorly helpful. I don't believe I've serviced one of these but I may have to a Mappy or something when I worked in Texas. @gamefixer provided me the insight about mixing the plugs and headers up, so +1 to him.