That's not a crt symptom. Flickering and lines are caused by the circuitry driving them. The most common cause is poor solder joints. Simply resoldering with fresh solder fixes a huge percentage of display-related faults. Much of my writeup on the Plus applies generally to the SE as well (see http://68kmla.org/files/). It may help you to know that I have disassembled many dozens of compact macs at this point, and I am not dead.
So, give yourself a Christmas present and fix that SE while you're upgrading the Classic. Once you've gotten a couple of successes under your belt, your trepidation will fade away. You'll be an old hand in no time.