1.
Feeder
Glass too cold
Foreign object on forehearth floor
Broken refractory in forehearth/spout
1.
Feeder
Raise glass temperature
Remove the spout cover and check for foreign object
2.
Machine Set-up
Microscopic inclusions from
Plunger (NNPB)
From excessive swabbing
Reheat time too short (NNPB)
2.
Machine Set-up
Change Plunger
Reduce the frequency of swabbing
Lengthen reheat time