actually nearly every emac and imac g5 produced between end of 2003 and end 2004 had potentially the bad cap issue , so the only ones not effected are the emac 1.42 models as they came out after the issue ,
but its not all that bad as its sound , most had been sorted by the repair program under extended warranty by apple back then ( ended 2008)
or died silent over the years , so there cant be many left with bad caps out there
but even if you are unlucky and catch one , the caps cost about 20 dollar and you can get them soldered in a good tv repairshop for a hour rate
and 2 of the bad caps are easy to spot (there are a lot more inside but these are the easy to spot ones ), open the emac on the bottom where you insert the ram and just below the bottom ram module are 2 of the most common bad caps
so if you can spot the black ones with coppergold stripe and X on top and they look like the ones in the picture leave it, even if the eMac is still fully working its only a matter of time before it stops working