I haven't read all the posts so this may have already been suggested: either a squirt of Dawn dish soap in water with a microfiber cloth; of half Dawn/half vinegar (warm it in the microwave first to help blending with Dawn) and the microfiber cloth.
I think the tag line for Dawn could be changed from 'it takes grease out of your way' to 'it takes grime out of your way.' I use it more for cleaning than dishes.
If neither works, it is time to go sew :-)