Replies to such old threads are likely to be a bit curious.
Mostly as to a reason why they are brought up, now.
The link to XLR8 page shows an earlier iMac G4 model
and that is slightly different than the last iMac G4 USB2.0
(15"/17'/20") models. They tend to be more like this inside:
•Mr Totes iMac G4 USB2.0 take apart:
http://www.mrtotes.co.uk/page1/page1.html
Thermal paste and other steps are required with access
into these layers where the 3.6V 1/2AA lithium battery,
and factory RAM slot, HDD, optical drive, etc, are located.
•3.6V Lithium 1/2AA PRAM clock battery, example:
http://eshop.macsales.com/item/NewerTech/BAA36VPRAM/
Also, the 17"/20" can use 2048MB RAM when both slots
get upgraded to 1024MB each, respective to type in each.
The bottom slot uses the same SODIMM as the last iBook
G4 (mid-2005) does, as an upgrade, exact in specification.
The power supply can be tested via small ports in the bottom
under metal plate (by reset button, by airport card slot) to
see if the power supply has failed in one of its voltages.
Anyway, curious to see an old thread come up like this.
In any event...
Good luck & happy computing! 🙂