Vidiot bottom left knob issue

I have a vidiot that has a very stick bottom left corner knob. The top of it does not spin freely like every other knob on the unit. Turning the top turns the bottom as well. I also do not have a full range to turn it, it just gets super tight. I was told to ask here. Thanks for any help!

Thanks for the message. Does it help to pull up on the top knob body a little, so it doesn’t rub? It sounds like the knob is just pushed down too far.