Dennis may well be right.

I came across a bunch of faulty eMac 1.25GHz computers, 7 have been successfully repaired by replacing the 8 dodgy capacitors (a well known and documented fact), and a further 4 still need repair. My guess is that the computers all still require further soldering, as Dennis alluded to. When I find the time, I'll take them apart again and touch up the soldering.