The main issue with this model was bad capacitors (cans), There are about twenty-four of them on the logic board. Take a look at them and see if any are swollen and/or leaking, or have bulging tops.
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'''Update'''
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Jim Warholic is the definitive authority on this issue. I'd read through what he has to say on it here:
The main issue with this model was bad capacitors (cans), There are about twenty-four of them on the logic board. Take a look at them and see if any are swollen and/or leaking, or have bulging tops.