This Potentiometer Keeps Catching Fire And I Can't Locate The Short
Obviously, too much current is flowing through the series R42/VR9 devices. A quick and dirty fix: if the VR9 pump control setting does not need to be at minimum rotation (0 Ω), and if the rework station functions normally other than the burnt pot, make R42 larger, perhaps 10kΩ. The issue might have been poor design, where too much current is passed when the pot is set to minimum.