Sorry for digging up an old thread.
One question. After the hi pot test was the secondary shorted out to a ground to remove the DC voltage?
I believe from my own experience Clive is 100% right. The hi pot through the coils and the secondary will hold a charge after the test and must be bleeded off or an unpleasant jolt will occur. Not like 120 feels more like an electric fence. Wanna know the feelin I'm talkin about grab both leads of a meggar and let your buddy give it a crank. Lol
In writing this post I have another question. The transformer was hi pot tested. Why was the secondary not removed before testing? Makes no sense to me. Not only will you damage the secondary conductors but you will also show bad at the can if it's a secondary issue. Me personally I would hi pot with the secondary disconnected and if that checked out I would meg the secondary.