Sent faxes have vertical lines

The 6012 has a small glass strip under the automatic document feeder (adf) that needs to be cleaned. If it's dirty it will cause the stripes you describe. Lift up the lift the cover of the adf, now lift the lid as if you were loading an original on the glass. Lift the adf feeder mechanism (lower half) there you will find the glass strip. Clean it with a damp sponge or rag with windex or other non-abrasive glass cleaner. Do not spray glass cleaner on the strip. Close it all back up and that should take care of your problem if not let us know! Thanks for using fixya!

This can be a dirty feed roller or your scan assembly may be damaged causing one area not to be scans correctly when sending the fax.