HP LJ 4000 Repetitive Defect Question

[dforcey]

I have a LaserJet 4000 with a repetitive defect measuring in at 2-15/16". From the Repetitive Defect Ruler on PrinterTechs.com, this distance indicates either the Tray Feed Roller, the Separation Roller, or the Fuser's Upper Hot Roller is at fault.

I've fed a sheet into the manual feed and turned off the printer when halfway in and there is no defect on the sheet (pre-fuser), but how do I know that I'm not bypassing a problem that may have been introduced by feeding paper from a tray (by using the manual feed)?

In other words, does my test confirm with certainty that the fuser is the problem?

Thanks in advance,
Dave

[Big Al]

It is very easy to pull the fuser out of this printer. Inspecting it may show the problem if you do not have a spare to swap into it. The measurement of the repetitive marks usually points to the fuser, the other mentioned sources are rare. Before you pull it out let it cool a little while and make sure the power is turned off.

Al

[redcow]

Listen to Al.
I have worked on laser printers for a long long time. I have never ever seen repetitive marks put on a page by feed rollers. It just isn't going to happen.
Pull the fuser and look at the rollers. One of them is probably damaged.

[DavidM]

The only other thing that I've seen that can cause repetitive marks is when something gets on the drum in the toner cartridge (like sticky from a label or recycled toner cartridges). But if you did the manual feed test, the only thing is the fuser.

[prntrfxr]

since you did the half page test from the manual tray, why not do it from tray 2?

easy to take the fuser out. look at it.

p/u, feed and sep rollers dont mark the page unless toner has dumped down in the tray cavity. Physically look at the rollers. Do they look dirty?