[Kevin Kuehn]

If the center spot on the CRT is only visible when the tube is lit, it's not a burn, but rather vaporized metal has been deposited on the back side of the phosphor. The deposited material is causing that area to shield the electron beam from lighting the phosphor. That's what happens if the set gets operated for a long time with the Ion trap improperly adjusted. That CRT seems to have fair brightness, although if it won't focus well it's possibly also the result of it being operated with the Ion trap improperly set. Once the electron gun aperture material becomes vaporized there's no way to fix it short of replacing the gun, otherwise you live with it as-is. If your high voltage isn't up to spec that could also be affecting the focus. I'd say you've got very good life signs considering the all original caps.