I've acquired a couple of 9" monochrome CRTs with the intention of transplanting. I've seen it done, but wanted to go through the steps all myself.   I'm starting with a used green-phosphor Matsushita CRT that came out of a CNC machine. A little burn-in, but I've got it, so might as well pop it in.   We'll start with hurdle #1 the fitment.  As you can see, the original CRT on the left sits lower, so some stand-off construction is in order.