NQ70M9770D - Knob on the control panel won’t turn smooth
I have a built-in microwave combo oven (chef collection). A knob on the control panel for the microwave is kind of stuck and won't turn smooth. I have to force to turn. I pulled out the knob and checked. It is almost new w/o any sign of wear and tear as I only started to use since Nov 2018. The same knob works well when I switch to the oven control. Can you pls help?