Recently my tower was hit by lightning. All my ham gear survived except
one. Since I forgot to unplug my Amp Supply LK-500ZB Linear Amp from the AC
power mains, the lightning found a nice way in.. (The rest of my ham gear
was disconnected from the power mains and the antenna)

I wasn't sure whether that amp was affected. But when I turned it on the
plate voltage was about half the normal value and the tubes were half as
bright.

What is the best way to troubleshoot and repair an amp that was damaged by
lightning NOT through the antenna BUT through the AC power mains?

What components will likely need to be replaced? Just the caps? What about
the transformer?

Is it worth repairing in the first place?

73's
Rob