My dad has a 2005 Saturn Relay with the 3500 V6. 125000 miles and runs great except it appears to have a charging problem. It seems any time the engine hits around 3000 rpm the headlights and the dash lights start flickering. The charging voltage also seems a bit high at around 14.5 volts. There's a TSB for the external voltage regulator and that's what I most often come across as the most likely culprit. Are they hard to change?