In the 1980s i learned first hand how much better mining service rebuilt electric motors lasted when the had been redone with "VPI" insulation.

Vacuum- Pressure Impregnation is where they rewire a motor, then put it in a vacuum chamber and pull out any trapped air bubbles deep in the windings.

After such a good "sucking" they let liquid epoxy insulation flow in from the bottom of the vacuum chamber and submerge the winding, then from the top of the chamber it is pressurized with nitrogen to force the viscous epoxy completely into the spaces around the wires.

The winding is then removed from the chamber and baked in an oven to set the epoxy.

This makes a waterproof and highly vibration resistant motor.

Is there a rebuild shop anywhere in the
USA or Canada that routinely does this
VPI for their reman alternators?