Holy cr@p!! that is pre-2000, pen assignments were using a PCP file (if I remember correctly). I don't know what to tell you, it's been way too long since I've dealt with that.
Maybe someone else has some advice.
BTW this thread is in AutoCAD LT - General and you added (chose) the prefix to your title: 2016 "2016: Why do the lines in my drawing print so faded" and so that leads us to believe you're using "AutoCAD LT version 2016".