iMac flickering screen

[Mary C. Youra]

My daughter, who is away at college, called today complaining that her 
iMac's screen is flickering. She has an older iMac (with CRT), indigo I 
think--either 2000 or 2001, OS 10.2.6, 384mb. I ran a search of 
Knowledge Base documents, which retrieved one that mentioned 
interference from fluorescent lights or other appliances. She has now 
tried plugging her dorm refrigerator into another outlet, as well as 
her desk lamp, but it hasn't made a difference. (For good measure, she 
also unplugged her computer for about 15 minutess before reconnecting 
it.) Since that didn't help, the KB doc said to take it in for repair, 
which is our next step when we visit on Friday. I'm wondering, though, 
what we're in for. Does anyone know what might be causing this?

Mary Youra