Copies and Scans have vertical lines

What model do you have?  All we can do is guess or offer general suggestions without it.

Dell 966aoi 4-in-one. 

 

Scans and copies have the lines, but not printouts from the computer.

If it's not "dirt" on the glass then it would be a hardware problem in the unit.  If it's in warranty call Dell support.  If it's out of warranty, Dell doesn't have a repair facility but since they are made by Lexmark, you MAY be able to get service at a Lexmark service center.  However, repair services can be costly and many times, as bad as it sounds, cost wise it's better to just to buy a new one.

New report:  I discovered that there were no lines if I did a one page copy or scan.  So I cleaned out the stack area (where you load for multiple copies).  So far so good, no lines.