How to install new air valve in 2006 Sundance Optima?

[pg_rider]

Hey folks, one of my air valves (that feeds air into the foot dome) on my 2006 Sundance Optima went bad.  I bought a new one online but I'm not sure how to install it.  Below is a pic.  Obviously it screws in, but how do I get the old one out?  Just grab the outer plastic ring with pliers and twist?  Any other tips / suggestions?  Do I need to remove the plastic nut first?

[Jacuzzi Jim]

 You have to change the guts of it not the whole assembly.    By no-means start cranking on it with a wrench!  This would be a bad thing, take the cap/handle off and you might have to pry the old inner part out then put the new inner part in. 

[pg_rider]

Well, I quickly realized that you need to take the side cover off the tub to replace the entire valve assembly.  Of course, the old one is coated in spray-on insulation and would be a major pain in the ass to remove.  So instead, I removed the "guts" of the new valve (i.e. the little black part inside the gray part) and transplanted them into the "housing" of the old valve.  All is well.