Reply to anyone have a stiff spot in their knob?

my vci-100 came in today . first thing i noticed was the left jog was louder and bit looser than the right. but i found on youtube a possible fix. now after playing around with it, i noticed the first fx parameter has a stiff spot at about 3/4 turn. its annoying because it gets really stiff there and its impossible to do an even sweep around the knob.

is there a way to clean the knobs out? or do you believe it will loosen up? has anyone else experienced this?