If problems are detected during regular maintenance and inspection of your VFDs, but the drives are still operational, you also have the option to refurbish the drive. This process involves changing all electrolytic capacitors on the circuit boards and the main capacitors on the DC link.Loose power cable connections, which originate from extreme overheating and too many mechanical vibrations, affect the VFD's operation. Extreme bus fault, a condition caused by instantaneous spiking voltage, is a common cause of VFD failure.