IMac screen appears to have smudges under the glass. They are not on the surface and it doesn't matter what wallpaper is in place.

Question

iMac screen appears to have smudges under the glass along the top of the screen.  They are not on the surface and it doesn't matter what wallpaper is in place.  Anyone else had this happen?

Answer 1

The " glass" front of your iMac is really not glass, at all, but an optically clear polycarbonite (plastic) that a black border painted or possibly "printed" on the backside (to hide the strong magnets that hold this cover on) that has a metal frame glued to the back to which this frame is held in place with very strong magnets.
You use one or two small suction cups or a suction cup from a windshield mounted mobile GPS mount or purchase a small commercial glass cup, that is used to handle bare glass, to get the polycarbonite frame off.
The reason I mention the material is polycarbonite is that you should NOT be using ANY type of retail/commercial window glass cleaners on this front glass or on the LCD screen.
Polycarbonite easily scratches and clouds when using ANY conventional glass cleaning solutions.
You need to use a lint-free, microfiber style cloth dampened in warm water (completely wring the water out of the microfiber cloth to the point cloth is just warm and damp with NO water dripping at all from the cloth) and use this to get the screen and glass don't screen clean.