Please read section 5.2 in
(thanks to @ankur for this SOP)
What sort of inspection system installed on strip packing machine, like any NFD (non filled detector) or checkwiegher, or camera inspection. Is it having anything or not having any of the above inspection system. if you are getting frequently then all these above should be challenged (if having) and machine setting, visual examination to be strengthened.
Let me know if you find this useful.