1. Feeder Incorrect glass temperature Uneven gob temperature   1. Feeder Adjust the glass temperature Adjust the forehearth so that the gob does not curl   2. Machine Setup and Operation Uneven cooling of blank molds Incorrect drum setting Excessive blank cooling Settle blow time too long - corkage reheat too short Counter blow time too short Machine speed too low Incorrect timing of gob delivery   2. Machine Setup and Operation Apply cooling air evenly on the blank molds Adjust drum setting Adjust blank cooling Reduce settle blow Increase counter blow time Increase machine speed Check loading position and gob delivery   3. Mold Equipment Blank design unsuitable - incorrect blank shape Incorrect plunger design   3. Mold Equipment Adjust blank design Adjust plunger design