According to Uniserver, it is the ENLA capacitors in the LC Series Power supply that always fails, while the other caps seem to remain rock solid. And he is not the only reference I have seen on this. It is these (4) caps that Ferrix97 replaced.

Here's Uniserver's page on the LC power supply: http://maccaps.com/MacCaps/Capacitor_Reference/Entries/1990/10/15_LC_I%2C_II%2C_III_Power_Supplies.html