I have a grey/black line all the way down the right hand side of the page

If the lines go all the way down the page, check the position of the corona wire cleaner tab (blue or green) at the top front of the drum unit. if not parked fully to one side it will create a solid black lines where it blocks the laser. Otherwise look for some other foreign object (or torn paper piece) that may be blocking the laser from the drum. If the lines are thin and shark, check for scratches on the drum (not repairable without replacing drum). If the lines are uneven thickness but in a pattern that repeats down the page every few inches, then the film on the drum is probably worn or wearing away and the drum needs to be replaced.

remove toner and drum unit
remove toner
check to see if there is toner in the drum unit if not fill unit run 5-10 prints
replace dev roller
replace drum cylinder(opc)

Needs Drum If you pull the drum unit out you will see on the drum different shades of color lighter is wear the lines come from. Buy a rebuilt drum much cheaper and they work, may have to reset the drum count if the change drum lite on...

There will be a flap at the back that drops out and down to give access to the fuser for clearing jams and "straight through" printing. Four lines repeating down the page is equally likely to be be a mark on the cartridge drum, possibly from the Primary Charge Roller if the unit has been very hot or not used for a period of time in higher temperatures. Remove the toner cartridge and in LOW light manually rotate the drum using the gear at one end of the cylinder. Look for a scuff mark right across the drum or a black/grey line. You may be able to clean the drum with a cotton ball and alcohol. Try the print again and see if there is any improvement. If you have another cartridge in hand you might try that to verify cartridge or fuser.

Try cleaning the charge wire. Move the lime green plastic handle from one side of the image unit to the other in the groove. If this doesn't work you'll need a new image unit.$$$$$. note: Make sure green handle is moved completely to the right when finished or black line will occur.

it may have had a dirt inside that may have been causing the lines. try cleaning with a soft dry cloth then try to print. reseat first the toner before you clean or wipe with a soft cloth

it is problem your copier scaner mirror is derty
clean it

Trailer socket pin1 (yellow) to left hand indicator (Black/White) at L/H Lamp, Pin2 (blue) to fog (Grey/White) at R/H Lamp, Pin3 (white) to Chassis Earth, Pin4 (green) to right hand indicator (Black/Green) at R/H Lamp, Pin5 (brown) to right hand side light (Grey/Red) at R/H Lamp, Pin6 (red) to brake (Black/Red) at either Rear Lamp, and finally Pin7 (black) to left hand side light (Grey/Black) at L/H Lamp.

all parts are ok just clean the printer it will work

There is a tiny spec on the scanner glass. Cleaning it will make the line go away.