Update: The pump was a direct drive landscape one made by Beckett, intended for...waterfalls!
The seal between the pumping chamber and motor is fubar. Eh, no big loss, it was free.
The video card, a radeom 8500, has an ugly burn mark around the leads of a capacitor. I've washed it well and set it to dry in front of a fan. Whatever.
The heater core -
Looks like a solder joint gave way between a tube and the end tank - water flowed out readily when I put it on a pump. After twenty seconds work with an oxy-MAPP torch, it's been pressurized to 10 PSI and is sitting in a bucket of soapy water. Now it knows who's boss.
All in all, it wasn't
too bad. Nothing important was destroyed, and I only lost seven hours of folding before if was back up. Plus, I had a chance to show off my purple-prose.