1. Feeder Glass too hot   1. Feeder Adjust feeder temperature   2. Machine Setup and Operation Neck ring not closing properly because of carbon accumulation or glass in ring Finish and locking thimble not engaging correctly in the guide ring Plunger up pressure too high (press and blow) Blank closing pressure too low (press and blow) Bland supporting mechanism worn Wear on mold opening and closing mechanism linkage Improper timing of the machine   2. Machine Setup and Operation Change neck ring Change thimble and/or adjust height of plunger mechanism Reduce pressing pressure Check blank closing pressure Change blank supporting mechanism linkage Change linkage on blank closing mechansim Check loading position and timing   3. Mold Equipment Blank mold recess for neck ring too large or neck ring diameter too small Neck ring, finish guide ring or finish thimble worn or dirty or out of dimension Interference between tongue and groove of neck ring Blank volume too small for glass weight and plunger size (press and blow process)   3. Mold Equipment Check against gauges Renew neck ring Check clearance between tongue and groove, neck ring and blank Check blank/plunger volume (press and blow process)