I'd recommend switching out analog boards before you try to use it again. Try to find a working SE/30 analog board to use while you deal with the one in the machine now. And, if the screen still zaps you, then you'll know that it's the CRT that needs replacing.

Or, if you don't want to get a whole new analog board, there are tons of people on here that would gladly have a look at the Mac for you, most notably Phreakout.

-Apostrophe