Cable is way conservative, it is rated for 40kV, and the standoff rings are a common TV part to psace the 35kV EHT away from things, but here they likely only go to 6kV or so, Most PAT is 2kV for 30 seconds, so they really went overboard. Toroid looks like it is the mains input and the big paper wound transformer is probably the EHT step up transformer, with the big board of darlington transistors driving it. 7 in parallel with current sharing resistors, and only a low power driver and that size heatsink with fan definitely means they get quite warm.
But soldering in the 3 push connection relays, instead of simply using a few short fly leads, means it is going to be hard to replace one when they do fail. QC 12 12 12 either is the checker number (12) or it was made in December 2012, but then this is a really old design to not have done the change to SMD on the main boards to reduce at a minimum the component cost.
