Tacx Satori - Mental Metal Noise

Hi there,
Santa brought me a Tacx Satori turbo trainer, which I'm confident that I've set up correctly, however!!!!
When changing the level of resistance through levels 5 & 6 it sounds like a disc grinder is engaging on a metal object!
Other than that it's perfect. If I set it in level 5 at the start it will work just fine and I can go through the gears on the bike but if I change the resistance into 5 or 6 during a session I get that mental metal sound!
Any ideas would be great if anyone has ever experienced something similar.
The uk importer isn't open again til Jan 4th n I'm impatient!