I recently purchased a 545A with a 1A2 plugin on eBay. The seller had posted a video showing the scope powered on and a trace on the screen, but that was 3 months and ~2,000 miles ago.
Visually, the scope looks OK (it was very well-packaged). I'm eager to start it up, as soon as I can install a modern power connector, since it didn't come with the original power cable. Before I do, are there any standard "pre-flight" checks I should be aware of for a tube-type scope?