Since the Navigation DVD keeps having "Please Check Navigation DVD" too often, I decided to remove it, opened it up and see if I can clean the laser head. It was a blind clean and ... I actually bought a new DVD unit from China (waiting) to replace. I have the Apple CarPlay working with touchscreen, I don't really need the primitive navigation system any more but too late to cancel the order. In case the new unit replacement work, this is how to remove the dvd drive inside the DVD. If the navigation works intermittently, leave it alone, not much we can do and it's not the copy or the original DVD because I tried them both.