I have a 2007 HUD - I rarely use this feature - but I am picky in that I like everything to work.  My HUD had been broken for some two years - first the image was crooked, and then the mirror must have come loose.  Read about the funky mirror pivot pin breaking and needing to replace this pin with a metal one.  So, that is what I was looking to do.  But when I had the HUD apart I found that some of the mounting screws had melted through the mounting bracket.  Now I live in Northern Virginia - it gets hot here but NOTHING like Florida or Texas and those Southern States.  So just used some small nuts and bolts and washers and got it working again.  I now plan to make a cover that will extend 2-3 inches beyond the HUD window that will simply be a foam board covered with reflective aluminum foil to cover this area when it is parked in the sun in the summer.  Hopefully this will solve any further problem.  Thought this might be helpful for those of you who live in these much hotter climes.