VFD IGBT blew up and I can't find a replacement part
I would be concerned that the diode junction to case thermal resistance is 2.0 deg C/W for the Fairchild device vs. 0.85 for the original device. In a VFD driving an induction motor the diode carries a significant portion of the current because of the reactive component of the motor current. If you decide to try the Fairchild device, you should probably set the VFD switching frequency to the lowest value.

Trying to improve the life of a product by tinkering with the design is never a good idea. For any electronic product, the best way to improve the life is to try to keep the internal temperature as low as possible. Be careful about mounting it in another enclosure, in a confined space or in direct sunlight. Make sure the space where it is operated is well ventilated. Consider setting the switching frequency to the lowest value, although that may cause the motor to operate at a higher temperature.