And to add something else, with regards to the crackling screen...my Macintosh Plus works great, except that it crackled once as well. Turns out it's relatively normal and shouldn't cause any problems--not for now, anyway.

Here's that thread.

viewtopic.php?f=7&t=11450

And Mac 128's right about that circuit board that may have fallen off. Macintosh SEs have a small circuit board attached to the very end of the CRT, and the connection isn't too secure. I almost pulled it off once; all I had to do was gently push it back into place and it was fine.

And listen--don't be afraid to open Macintosh SEs. I have four Compact Macs and I have opened each twice at the very least; most of them I've opened four times or more. And most of those times I've removed, reinstalled, switched, or replaced several different vital components. All you need is a Torx-15 screwdriver and a bit of strength to pry the case open. There's really no need for concern, as long as you're mindful of delicate components and electrostatic discharge that may damage disk drives and other circuits. You'll be fine.

Hope that helped,

-Apostrophe