Hi LePaul no its not the filament. The sound is coming from the X and Y stepper motors or the pulleys. I'll try cleaning the belts and pulleys. I think I'm going to get a stethoscope to help isolate the noise if it keeps up.
I have two UM 2 Extended printers and they both get fed by the same version of Cura but only one has the problem.
Thanks for your reply!