i had an imac slot load 500mhz fail from heat. I never could fix it so i trashed it.

it would power up just fine, but then after a little bit, you could see the picture pulling in on the sides of the CRT, basically the horiz sweep was starting to loose its width. then it would suddenly pull in much faster and poof. machine would shut off. resoldering every solder joint and testing every capacitors ESR didnt turn up the issue. so i junked it.