Hmmmm. Was the bottom heatsink epoxied to the box? It looks like the thermometer readout was epoxied in place on the top cover too?
My junkbox had a whopping big aluminum heatsink from an old mainframe supply - 5x5x1.5" with large fins on both sides. I can mill a flat area near one end to accept the existing heatsink with some heat transfer goop. I knew that if I threw it out that I'd need it someday.
Now to find a big fan/blower and a box to put it all in. Maybe remount the thermometer so I don't have to do handstands to read it.