Model 600. Why is it dropping toner near transfer corona unit?

Kenneth:
I would remove and cover the drum carriage (to protect the drum from damage by exposure to light), and check and clean the corona wires. There is a charge corona and a transfer corona, so that's two coronas that you'll have to clean. If you can remove the coronas from the machine, you can do a better job of cleaning the coronas. A faded line down the page like you're getting could be a paper shard stuck to one of the coronas... it's been known to happen.

Hi Usha

The possible causes
-charge corona
-drum in end life

The high voltage wire used to charge the photo-conductive drum is broken or shorted.

It will need to be repaired or replaced.
It is usually a fairly simple job, but you may need the replacement wires to complete the job.
It could be someone has pressed the scoritron grid tensioner and allowed the grid to drop onto the drum.
Great care must be taken when working around the drum area.
If you open the front of the machine.
drop down the transfer section (yellow or green handle)
flip out the toner bottle.
you should see to recessed screws, one behind the toner bottle, one on the far right side of the unit. loosen these all the way,
there may be a plug in each side to disconnect.
you should now be able to slide the unit out.

set it down in some paper, the corona will be the long metal housing stretching front to back on the drum unit.

Remove it by sliding it one way, then it should open like a hinge, open it all the way and it should pop loose of the main unit.
The corona wire is behind the grid, it is the thickness of a human hair. If it is broken you will need a replacement, if the grid was off when you opened the unit up reinstall the grid and reassemble.
If the corona shell or the scoritron is discolored, clean them with a glass cleaner and soft cloth.
Keep the drum covered with paper so it is not exposed to direct light for any great length of time, do not allow the drum to be exposed to direct sunlight.

This would indicate that you are having a transfer problem or the Paper is very damp. Have you changed the transfer corona wire?
Also check the drop down mechanism that holds the transfer unis. Mechanichaly if it is not in the correct position when in the locked position this can cause the problem that you are experiencing.

electrical noise / spark on one side of any corona unit or charging/transfer corona unit with tungsten wire. Replace the wire or put insulation on both rear or front blocks attach with charge wire.

Somebody put developer in your toner hopper. You'll have to vacuum out the toner hopper and clean out the developer. re-service the machine with developer and toner after cleaning out the mess in the drum cavity.

Fuser not cause light copy.If fuser problem the fuser unit not fixing the toner to paper (not fixing image).Light copies :dirty optical parts,Organic Photo Conductor drum,charge roller or charge corona wires or charge corona grid dirty,transfer/separator corona wires dirty.

Hi, you can clean the corona wire easy, just follow those steps:
1) Turn of printer power and unplug all cord including phone cord.
2) Make sure the scanner is closed, then lift open the top cover by its handle.
3) Remove both the drum unit and toner cartridge assembly for the color desired to be replaced.
4) With the drum unit removed, push down the GREEN lock lever to remove the toner cartridge.
5) Slide the GREEN tab left to right several times to clean the unit's primary corona wire.
6) Before installing new toner cartridge, shake it from side to side to distribute toner.
7) Remove protective cover from cartridge.
8) Insert cartridge into drum unit until it snaps in place.
9) Ensure that you are inserting the correct color toner cartridge into its proper place and then slide the drum unit into the printer.
10) Close the top of the machine and then reconnect all cords; turn on power to ensure proper installation.

first toner must must and must be genuine, other wise it wont work in any conditions,
2nd toner density sensors and gamma sensor should be cleaned and all auto setting must be run .
third some time toner drops down the others side of the drum due to recycle clutch did't not work properly and all cleaned toner drops down after filled in recycle area,

It is probably the transfer corona if you have already tried replacing the toner cartridge. The transfer corona charges the paper so that it will pull toner off the drum and it can go bad. Email HP and find out if the transfer corona is included in a drum replacement. If so, you need a new drum. If not, see if you can purchase and replace the transfer corona.

E067 Two or more faults in the primary/ pre (post)-transfer/ transfer/ separation high voltage are detected (including power output stoppage, electric leakage from the primary corona assembly).

Primary and/or transfer/sep unit leaking or arcing.

These are the units that have a very thin wire in them.