There is a well known problem with the windscreen in that sun will magnify and cause a hot spot on the tach and melt it.
No joke - it happened to mine. Strange but conditions have to be right of course.
If you bike has sat in the sun you may have a simple windscreen induced melt point.
Mine is seen as a small 7mm wide smooth spot on the top of the tach - at about 11pm and a distorted surface. I have no pics yet - but will go out and take one for you.
As your attorney, I advise you to buy a motorcycle. How else can we cover a thing like this righteously?