I have two Dyson Pure Humidity and Cool machines.  One is a little over a year old.  The other is just a few months old.  They are both up to date on deep cleaning.  The older machine just had its filters replaced.

They are both intermittently creating a grinding type noise.  When the noise begins it will continue until the machine is turned off.  Later when the machine is turned back on the noise  will eventually return and remain noisy until turned off.

Please advise what can be done.

Thank you.