LaserJet 6L paper feed issue -- The saga continues...

[JLanex]

I apologize for the topic that is the stuff of obituaries and museums, and twisted horror movies. I’ve been keeping this mean machine in my company for most of my adult life, but our exhausted relationship may just experience an abrupt and violent end. If it ultimately refuses to cooperate with me, I’ll back up on it with my car (risking a flat tire) or drop it onto icy concrete off the roof of a building with at least ten stories.

I’ve moved on from the infamous multiple-page-feed-gag symptom and achieved mild success with a few pages printed normally when around 8-10 pages are in the input bin. Sometimes. So I decided to disassemble the machine again to fidget and fine tune, and perhaps one day to enjoy a normally functioning printer. Poor choice on my part.

Condition of PARTS: I have replaced the pick-up roller, separation pad and the two small subpads. All are new. The two rubber wheels on the feed assembly seem OK. The paper out sensor (PS202) and paper registration sensor (PS203) are functional, not damaged (in my view), the one on the feed assembly moves unobstructed into position between the two sensors (2 tiny black boxes). The green light is ON when paper is inserted.

Right now I can’t print/test print a single page. As seen on the attached photo, the paper stops just before the shiny metal plate beneath the toner cartridge. The machine becomes still and there is no further mechanical movement (top yellow error light on). The paper can then be removed with moderate effort in either direction (it is not jammed).

Last position of paper when feed/machine stops

I no longer print much. I have a new toner. I would be happy with this printer, if it would finally hide its ugly side. I’m not planning to spend any more money on parts.

A kind contributor on this site (East2100) offered detailed solutions for similar issues to someone for a 5L printer.

https://h30434.www3.hp.com/t5/LaserJet-Printing/Parts-for-Laser-jet-5L/td-p/7483307

If there is anyone out there who can share his/her know-how or a tip on how to resolve this issue, I would really appreciate it. If not, the machine will RIP.

Thank you in advance, approaching, perhaps, a successful new year in DIY printer repair.

[Repairatrooper]

Based on where it is stopping, it is possible that you have a bad toner cartridge that is not rotating. This does happen, especially on old toner. I know you state you have a new toner but if it is an original HP and is over 8 years old the plastic cleaning blades might be bonded to the drum unit and stopping it from rotating. I have also had limited success with 3rd party feed rollers actually feeding properly due to the diameter of the roller being slightly smaller than actual HP ones. Does the paper start to move in on the first rotation or do you hear the pickup assembly rotate several times before the paper is actually drawn in?

[Valsimot]

 The two rubber wheels on the feed assembly seem OK.

Might seem OK, but probably rubber is hard and slick to feed paper properly. Use a cotton swab and alcohol to clean those two, you can use fine sandpaper to clean the surface of the rubber roller for better grip. If that helps then you will have to replace them with new one p/n RB2-1699-000CN. Some aftermarket kits include those rollers for a reason.

[JLanex]

Thank you for your reply, Repairatrooper.

1. Yes, the paper starts to move on the first rotation, then stops in the same position.

I measured the pickup roller with a caliper: roughly 28.5 mm. I also measured the original (worn) roller and it is also around that size. Obviously the new (3rd party) roller is ribbed (it has a bouncy, rubbery feel), the old one had a smooth surface from the beginning (if I recall correctly). 

I don't know what the required diameter should be, but I could perhaps remove the rubber ring and use electrical tape to incrementally increase the diameter. 

2. The printer produces the same symptom with two toners. I still have the empty original HP toner. The new 3rd party toner worked without fault while the printer was working, although on one end it is "loose", meaning that its two halves become detached and a small spring becomes visible (as shown on the picture below). This is how it came out of the box. I don't know if this is some new design. I didn't research this issue, because it was working (it fits normally into the printer).

3rd party toner with loose top

[JLanex]

Thank you for the reply, Valsimot.

Yes, I noticed that these rollers are also offered separately/in a package with the maintenance/repair kits.

I cleaned and sanded them with 120 grit paper. The issue remains.

The contributor I linked above used heat shrink tubing added to these rollers and claims it improves grip. Such tubing also has a smooth surface, though, but maybe the increased diameter does the trick.