EVERYTHING I PRINT HAS A DARK LINE ON THE RIGHT SIDE OF THE PAPER. WHAT NEEDS TO BE CLEANED?

check the fusing unit the hot part where the paper comes out? is the line a certain color replace that image unit.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f

Perhaps did not specify paper thickness (check control panel and print driver).
Toner getting low.
Clean registration roller with clean damp cloth.

clean that small glass on printer if problem still continue open all machine and try blow it blower machine!

Print is skewed

1. The rear access door might not be fully locked into place, causing the paper to skew in the all-in-one. Remove the rear access door by pushing in on both release tabs as shown in the figure below. Inspect it for damage, and then reinsert it. Make sure it is securely latched in place. Figure 6: Releasing the rear access door latch on one side Figure 7: The rear access door removed
2. The paper feed rollers may be dirty. Over time, paper fibers and dust will stick to the rollers and should be removed.
   1. Unplug the power cord from the back of the all-in-one and open the front to expose the print mechanism.
   2. Gently wipe the paper feed rollers with a soft clean cloth slightly dampened with clean water. These rollers may be rotated with the power unplugged.
   3. Remove the rear access door shown in the figure above and wipe the paper supply feed rollers. These rollers may be rotated with the power unplugged. Allow the water to dry for five minutes before reinserting the rear access door and locking it in place.
   4. Close the all-in-one and reinsert the power cord.

check the fuser... to see if one of the rollers has toner all over it... then check your paper path... to see if you see any obvious signs... then try printing 20 pages and opening the copier at various times during the printout process... you want to see if you can catch it where the dark starts appearing... chances are where it starts... is right next to the bad part... you are looking for a print out with one half no dark and the other half real dark...

I’m happy to assist further over the phone at https://www.6ya.com/expert/norman_d2fa496dce30c65d

I had a similar problem but it was only one dark line on the right side of each page. I just changed the drum while keeping the same toner and the problem is gone.

try cleaning all visible glass with glass cleaner

It sould be the print heads have gone bad.
I just had a Dell color laser that would print a 1" wide yellow line down the right side of the paper.
Replaced the print head unit, and problem solved.

If the print can be rubbed off then this suggests the fuser unit is not working correctly. It could be that the thermistor is covered with toner and making the machine think the fuser is hot enough when it's not.

The black line could also be caused by the fuser if one of the pick off fingers is coated with toner or has worn into the Teflon of the roller.

Does the machine show the lines when you print a page from memory - such as a counter or config page? If not, this would suggest the optical path is dirty. Try cleaning the glass and look at the mirrors inside the scanner to see if they are dirty/dusty.

On the ADF check the twink mark on glass scanning mirror