Agreed on adding resistors, but you would have to make sure the longer turn on time of KBID does not cause a problem.
Having to put a resistor inside the keyboard could be an issue for some. I finally got the stuck screw out of mine. I replaced all 4 screws with Robertson (square drive) 6-32 x 3/4" flat head. Of course I did not tighten them the way Tek's 300 pound gorilla did.
What a great idea to put the diagnostic ROM on the card. There is apparently a whole library of manuals for diagnostics, listed on page 1-1 and 1-2 of the 7854 Service Manual. We would need to start a search.
A 7854 was sold by Solanotraders on Ebay on Feb. 28, which included the 067-0961-00 diagnostic card (Version 4 if the label on the back of the scope itself is any guide) and the front keyboard diagnostic overlay. I wonder if Solanotraders would be willing to pass a message on to the buyer on our behalf, asking if he would be willing to communicate with us? The 7854 he bought is a candidate for the new memory card. Maybe he's already reading Tekscopes...