I can't tell you how many sealed or NM shaded dog and other lp's I have that have blotches of whitish grey residue that does not come off no matter how hard I scrub with enzymes, alcohol based surfactants and even 5% distilled white vinegar. Nothing seems to remove this stuff and it makes the record crackle when the stylus encounters these area's during playback. Does anyone know what I am talking about ? Does anyone know how to remove it ? TIA