CO2 regulator valve question

I have a quick question. I have a CO2 dual body regulator that came with my initial kegging kit. The pressure control knob on one of the regulators is extremely diffuclt to turn. I pretty much have to use a wrench to turn the knob to change my pressure.

What would be the best thing to help move the knob. Would it be safe to use WD-40, keg lube, regular vaseline, or something else to fix this.

Thanks!

If it were me, I would take it completely out and clean it and try it again. If that didn't work I would take the bolt to the hardware store and try to replace it. If that failed I would consider tapping the hole, cause it sounds like a binding thread.

WD40 is good, just don't spray it directly on as you might get it in places that you don't want . You can spray some into a small container then drip it on the threads. If you are not comfortable with taking things apart I would not do so, nor would I replace anything until you tried the simple method first.

Liquid graphite (Graphite suspended in alcohol) greatest anti-galling lube around.