I haven’t yet looked to see if there’s a replacement part available. It isn’t like the modern version, screws into the water jacket, works like a cooling system thermostat, wax method probably. I’d like to replace it b/c it causes the mixture to be overly rich on start-up. If I can’t find one I’ll probably replace it with a modern electric-solenoid version, and figure out a way to control it to open & close according to the coolant temp.
It’s looking a little sad indeed. But it is scheduled for some repair and maintenance work this winter, so won’t be totally ignored. And I still drive it, if I need to pick up some plywood, stuff that won’t fit in the Corolla.