What Would Cause an Alternator/Voltage Regulator to Fail Twice?

[Erik]

I had the lower fuel injector gaskets replaced recently. As it was not a job I wanted to undertake myself, I had a Corvette specialist dealer who still had some ZR1 knowledge do the job. On the way back home, about an hour into the drive, thr battery light came on and the voltage gauge dropped down. I'd had the alternator tested twice in the years before, and it had always passed with flying colours. The bearing had been a bit noisy, so that got replaced. But, as it was 30 years old, and the ZR-1 under hood area isn't friendly to things electronic, I wasn't too surprised. Took it back, they had the alternator rebuilt, and I was back on the road again. Survived the trip back this time, and all seemed ok.

Tonight, was on the way to the local car show, and the dash lights and Instrument panel flashed briefly. Weird, but all seemed ok and kept driving. About a minute later, I noticed the battery light was on and the gauge was showing low. Crap. Still running fine, but just off the battery.

So, as it wasn't a problem before the plenum pull, and I'm not a huge believer in coincidences, I'm wondering what could they have done that would cause the voltage regulator to blow twice? And seeing as how the plenum was off for some extensive work, I'd guess it was something there.

Any thoughts before I call the shop and start yelling?