HP LaserJet 4300N
I am getting random black smudges down the right side of every copy that feeds from the paper tray. Sheets that go through the manual (#1) feed do not have the smudge. I was about 3,000 copies into the current ink cartridge when this started. Do I need to replace the cartridge or is something else wrong?

Experienced technical support provide their insights in answering this question :
That doesn’t make any sense. Sheets that feed from the manual feed or the cassette tray both converge before the toner cartridge. That would mean that the smudges would somehow be put on the paper as it was feeding upwards from the tray. There is nothing in the printer that could account for that happening.

How to Identify and Fix Common printer Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced technical support :

Smears and smudges on the paper can be caused by dirt, dust, or toner accumulated on the rollers or transfer belt as it passes through the paper. Cleaning your printer, particularly the rollers, is one of the options for removing black markings from paper.
Smears that appear in addition to otherwise well-formed output may signal toner contamination inside your LaserJet, either from a leaky cartridge or from improperly fused sheets that leave toner residue behind. Smears at the edge of the sheet that enters the printer first point to dirty paper guides.
The best way to prevent smearing is to make sure you give the ink time to dry before picking up the copy or copies. It doesn`t take long, maybe 10-15 seconds. If that doesn`t work, try changing your printer settings for a lower quality print job. You generally have a choice, Best, Normal or Draft.
What`s happening is that the drum or rollers could have a fingerprint or dirt that is smudging the toner on the page as it passes through to the fuser. It is normally caused by the rollers. If the marks are always in different places, then it`s most likely to be the drum.
Dirt, dust, or toner accumulated on the rollers or transfer belt can cause smears and smudges on the paper as it goes through the paper. Cleaning your printer, especially its rollers, is one of the possible solutions to fix black marks on paper.
Dots are typically caused by foreign material inside the machine (for example, paper dust, glue from labels or envelopes, paper clips, staples) sticking to or damaging the surface of the drum. Toner builds up on or sticks to these areas on the drum and creates black dots on the printed pages.
Streaking is usually caused by a worn out drum unit or spent toner cartridge. Drum units are a consumable and only need to be replaced after the use of 3 or 4 toners. Not all printers use a separate toner and drum unit.
The problem may be due to a simple issue like printer paper quality or ink/toner cartridge wear, or it could be a more serious problem that requires professional repair.
Your printer can become misaligned if there is any paper stuck in the machine, print cartridges are clogged or dirty, improper installation of cartridges and using low quality cartridges. Additionally, a printer can become misaligned after the machine completes a large print job.
Make sure the printer platen is not dirty with ink. Unplug the machine from the AC power outlet. Lift the scanner cover until it locks securely in the open position. Clean the machine`s printer platen(1) and the area around it, wiping off any scattered ink with a soft, dry, lint-free cloth.
Dots are typically caused by foreign material inside the machine (for example paper dust, glue from labels or envelopes, paper clips, staples) sticking to or damaging the surface of the drum. Toner builds up on or sticks to these areas on the drum and creates black dots on the printed pages.
Bleed refers to an extra 1/8” (. 125 in) of image or background color that extends beyond the trim area of your printing piece. The project is printed on an oversized sheet that is then cut down to size with the appearance that the image is “bleeding” off the edge of the paper.
Faint, streaky or spotty prints are all common signs of a clog but a simple cleaning can usually get your HP ink cartridges working again. Printheads clog due to infrequent cartridge use. If you regularly go a few weeks without printing, your cartridges will eventually dry out and need to be replaced.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

My printer feeds through one piece of paper all the way and then a half piece of paper and stops. I pull out the paper to stop the paper jam and then it prints but sounds rough. After printing, it doesn't feed the paper all the way through.
ANSWER : And the first 2 sheets, the full and half sheet that go through first, are blank.

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HP LaserJet 4300N

Smudges down right side of paper
ANSWER : That doesn’t make any sense. Sheets that feed from the manual feed or the cassette tray both converge before the toner cartridge. That would mean that the smudges would somehow be put on the paper as it was feeding upwards from the tray. There is nothing in the printer that could account for that happening.

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HP LaserJet 4300N

paper will not load right, only on the left side then jams. Worked fine this am, 2 hours later this happens
ANSWER : There is something in the paper path on the right side blocking it. Could be a torn scrap of paper, a dead bug, etc. Use a piece of file folder to push it out.

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HP LaserJet 4300N

Workforce 600 continues to bend corner of paper then jam where the sheet passes through the metal platen at the right side of printer.
ANSWER : Everytime that I have seen that happen it was because there was a small scrap of paper in the paper path on the side of the fold. I have dislodged hundred, if not thousands of them by shoving a thin, flexible plastic stick down the paper path. You can also cut a piece of file folder to size and use that. For small scraps of paper, it is usually stiff enough to clear the obstruction.

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HP LaserJet 4300N

Rear Paper Feed Blocked On Left Side?
ANSWER : Most times it is something you can’t see, like a small torn scrap of paper. What you can try is to shove a file folder down the path the paper takes. That will push out any offending scrap without having to take the printer apart.

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HP LaserJet 4300N

Black line down right side of page
ANSWER : The black film is the upper fuser roller. You need to replace the fuser unit. Not hard to do. Remove the back “door” and flip down the two blue levers. The fuser will slide straight out.

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HP LaserJet 4300N

paper drive wont accept paper
ANSWER : There is probably a small scrap of paper stuck at the left edge of the paper path. The paper hits it and skews to the left. The smaller size bypasses it. You need to shove something stiff, like a piece of file folder, down the paper path and attempt to dislodge it.

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HP LaserJet 4300N

Error message to load paper and push OK, but not out of paper
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HP LaserJet 4300N