Larry wrote:

Can one tell if a pwr xfmr is good or not by measuring the (unloaded)
primary current? I have a large surplus unit that I want to use for a
project. It's rated for lots of current and weighs over 11 pounds.
When I measured the pri. current, it was 0.31A at 120VAC with no load
on the transformer.

That could be reactive current. Unloaded, the transformer will look
like an inductance
to the AC powerline. And draw reactive current. This is current 90
degrees phase
shifted from the voltage waveform, and does not consume power.

One way to check this would be to use a "Kill-a-Watt" power meter.
Radio Shack
has (as of a few months ago did) these for $40 to $50.