My question is, what is the easiest way to get to the nut? I am reluctant to start dismantling the interior, as it looks like the dash and the trim roll underneath it will be in the way. Has anyone found a simple way in, please?
If the CX screen frame is similar to my Roadster, then yes there is a nut holding a penny washer in place at the end of the allen screw. In my case it had vibrated loose on the passenger side, and after trying everything else I dropped the dash. I have since done that a few times for other jobs and it's not difficult (certainly on Trads) nor scary. With the dash lowered you can easily access the errant nut, and reach round the outside of the frame to hold an allen key. While in there, have a look at other bits that might need attention. Failing that, ask a baboon, as they seem to have no trouble finding their nuts
