Originally Posted by Johno1958
Motor has got no play and turns over smooth except ripply sort of feel like a stepper motor, but that's it for me ,they can fix it.
That "ripply" feel is indicative of some sort of problem - sounds like a permanent magnet (PM) motor with an armature winding short - could be as little as a single loop - but it plays havoc with the VFD. The motor fails to vector smoothly and sounds can vary from the delicate tinkling of tumbling broken glass to a cement mixer filled with scrap iron.
If it is a PM motor then you can test drive it with a cordless screwdriver (effectively driving the PM motor as an alternator) and measure the three output phase voltages (disconnected from the VFD for this test) one phase will be low - there's your problem.
You might also have a phase short.
If it's a squirrel cage rotor then none of the above apply and I'm baffled.