Hi!

Stick a heatsink on it. *Job done.

It's already got a goodly sized heatsink on it. In fact, I couldn't
find anything bigger in the TO-220 category. Operating temps turn out
not to be as bad as I thought--about 124F at most. Perhaps the
original regulator was just defective. I'll never know.

I will probably just run a fan from the other, less loaded regulator
and suspend it over the circuit board. That would be a lot less work
than milling some scrap heatsinks from old PC power supplies down to
fit.

William