The solution to the panasonic black stretch/modulation issue is to change a setting in the service menu. Doing so kills the modulation however it also ups the pedestal black level quite significantly. My advice is not to do it and live with the black fluctuation (probably panasonics way of cheating the contrast range depending on picture content. The black lift is more damaging to the picture quality than leaving it alone and it cannot be rectified even in the service menu. You have better blacks with the setting left alone.