I think bad PSUs on the iMac G3 are not so common, if you treat your Macs well... I've only one (600 Mhz) that has a similar problem. But it does make a strange "electrical" noise when I plus it in and try to power it up.
Juliet said that the power button needs / needed to be pressed more than once to boot it. Maybe it's really stuck (OK, I don't know why it should, but it seems to be! ^^)
I'd try first a keyboard with a power button, before you tear it apart for nothing. Take any old G3/G4 keyboard, a "coloured" one I mean. Later clear Apple Pro Keyboards don't have a button. (I think that a keyboard with button from the first Slot Loading iMac G3 series should also work, and so should a B&W Power Mac G3 Keyboard, etc.)
Juliet said that the power button needs / needed to be pressed more than once to boot it. Maybe it's really stuck (OK, I don't know why it should, but it seems to be! ^^)
I'd try first a keyboard with a power button, before you tear it apart for nothing. Take any old G3/G4 keyboard, a "coloured" one I mean. Later clear Apple Pro Keyboards don't have a button. (I think that a keyboard with button from the first Slot Loading iMac G3 series should also work, and so should a B&W Power Mac G3 Keyboard, etc.)