Inspect pressure between blanket and plate or between the blanket and paper
Pack to press manufacturer’s specifications
Blanket tension low
Tension current blanket (or new) to press manufacturer’s specifications
Grippers out of calibration
Check and reset all grippers to press manufacturer’s specifications
Paper with wavy edges or other distortions
Check on a different stock to see if slurring remains. If not, change stock or consult your paper supplier