Well, I got real lucky on this one. I stumbled across this fairly cherry 556, it took some negotiation and 100 bucks, plus access to a pickup truck and this baby was mine, cart and all. When I looked in the drawer I felt even better, 4 probes, all sorts of adapters and many probe tips and accessories. Plus an operators quick reference book for the 535\545.

After a careful eyeball inside I brought it up on the variac and was rewarded with that great aroma of hot vintage test gear, plus one trace. I quickly determined that the Type M plugin seemed messed up, the Type O seemed to function, and the lower beam was deflected way off, all I could get was the reflection.

A voltmeter confirmed my suspicion, the plates of the lower beam's final 6080 amps had about 100V differential on them. I decided to wait for the manual I had already ordered, and in the meantime to take a few "before" photos, and start a log on the resuscitation of this fine old o'scope.