I just bought a used HQ16. "Harriet" runs very well and has a good stitch. She purrs when she is sewing on manual mode

. But when I change the mode to regulated, she is like a chain saw.

My DH came from another room to see what the noise was..he said it sounds like it needs oil.
Does anyone have this problem, or could offer suggestions. Tomorrow I will try to talk with HQ people and see what they can advise me to do to quiet her....