You are welcome to call 805-466-8636 or 541-8600 for free tech support.
This lines diagnostic are for dry toner office machines, they are not for machines using inkjet.
1) If the line on the copy is only when you use the Document Feeder, but not when you lay the original on the glass:
lift up the Document Feeder and locate the space under the Document Feeder where the original pass above the glass, look carefully there is a smudge or even a pin size dot on the glass at this space on the glass, clean the glass with Windex etc.
2) If the lines persist using the original on the glass or the Document Feeder:
If your office machine is using a cartridge, replace the cartridge. If the line is still in the same place call for service, it is on the drum (photo conductor), or from the fusing unit.