Want to install an aftermarket add-on for HD radio. Instructions only say connect to the radio antenna. Online users say remove the A/C knobs to access the radio mounting screws but on my 2009 xB the A/C knobs appear to be held down by some spring loaded mechanism. I fear pulling to hard as I might break the knobs, void the warranty, etc. Anyone have any experience/knowledge about dealing with the 2009 xbox?