High temperature and overvoltage can be tough on electrolytic capacitors. Check line-side diodes to be sure one didn't fail, injecting AC into the DC bus/capacitor(s). Sometimes smaller VFDs become such a narrow-profit commodity that it’s cheaper to do a wholesale replacement. Some make good boat anchors—many do not.
62, What sort of cabling are you using between the drive and the motor?. Is there any Mains-borne interference on the wires feeding the VFD, these units need a perfect Sine Wave input or there will be problems. Unfortunately, you will need an oscilloscope, to see what the waveshape is like, any harmonic interference on the lineside of the VFD, cause wierd currents to flow where they shouldn't. Hope this helps.
Let's face it, these days if you're not young, you're old - Red Green
62,- This could be almost anything, like maybe a scr, rectifier, diode, or trim pot. Did you take it apart to see any possible over heating on the boards? Might be a good idea to call the drive's tech dept. for some help. did you disconnect motor leads from the drive before you meggered??
How much torque is on your load and what is your Decel time? If your decel time is too short you will have too much regenerative current feeding back into your drive. A properly sized braking resister might help. JMHO