Can you tell what the failure in the relay is? If it's the coil burned open then it's getting too much voltage which doesn't seem possible without many other issues cropping up. Are the contactors burned or stuck in one position? This could indicate something in the circuit drawing too much current. I don't know how much current should be present but you could measure it or have someone do so and compare it to another VX. If it's running high current then one of the components along the line needs to be replaced - not very specific I know.