Hi! Im new here and I have a question.

On my iMac DV+ the screen starts to "pump" and shake, and after 5 to 10
minutes the screen makes a "blink" and the iMac freezes.

So far i found out (with the help of a service manual) thath the
power/analog/video board is broken, but i think it's more like an
broken capacitor who causes this problem.

So my question is

How to identify this capacitor, or do I need to replace every capacitor
on that board?

Thanks