HP 4600DN Print problems

[Don]

I have a 4600dn that is acting quite qwerky. This color printer will print just fine provided it is only single sided. Anything printed in duplex the second side will be smear, with slight ghosting (IE on the blank section at the bottom of the page there is a very faint repeat of what is at the top of the page),the second side just enough to cause text to be fuzzy.
The Transfer unit and all four color cartriges and the static eliminator on recomendation by HP over the phone have been replaced with new items. I am leaning towards the fuser unit simply because I don't think there is anything else in the paper path to change. Any suggestions?

[MichaelTech]

Check the fuser area. Toner gets blown up there in the natural operation of this unit. Also check below the Image belt for toner. Remove the lower toners and look at the P/U area for toner spill. Check all toner contacts on the left side. The contacts should be bowed out.

[Don]

Ok, I have checked the requested areas and cleaned useing a toner vaccum (3M). The only thing I found is that the magenta cart. leaks a little if bumped. Contacts are good. Still same print problem. The condition is most notable in black and that cart. has been replaced with a NIB HP cart.
Thanks for your help on this!

[redcow]

Run the cartridge test. Remove all cartridges. Put the cyan in the blacks' slot, print some pages and see if the cyan is doing what the black was doing.

put the black in the yellows' slot, print and check o/p. If the black screws up no matter where you put it...it's bad. If other colours screw up up in the blacks slot ...the alienation rods may need to be reseated.

[woodss]

vacum the enitre printer till there is no more toner to vacuum, also blow the rest out with a air compressor, this will elimate the toner causing the problem.

as for the toner leaking try another magenta toner that does not leak thats bad.

Also check if the duplexer isnt dirty, you could be not checked the duplexer as the source of the problem if the pages are fine with single sided then the single sided paper path is fine and your wasting your time with the simplex paper path.

Its the duplexer that I would be looking at, make sure that the duplexer itself is clean, toner could have got in there causing this problem, it sounds like the duplexer is due for a clean.

Fuzzy printing is almost always caused by a fuser assembly, replace the fuser after cleaning the duplexer, it shouldnt make any diffrence if its in duplex mode or not.

Please note that fuzzy printing can also be caused by a faulty scanner assembly too.

[MichaelTech]

As Redcow advises, the cartridge check is best to find bad toner. One can't always replace ALL the consumebles, but it helps. And the fuser area does accumulate quite a bit of toner at the inlet.
Come back, good buddy. Fixed?

[woodss]

Testing does not make the problem go away, it looks to me its a cleaning issue.

If the printout is okay at simplex and dirty at duplex naturally the duplexer needs cleaning.

[Don]

After much money spent on consumables and other bits the fix is suprizingly simple. It was the paper!?!? We here try to do our part for the environment and use 30% recycle paper. It turns out that this printer (4600) and a few others are a bit sensitive about the paper they digest. Went to the store and bought HP general use laser paper and the problem disappeared.
The owners of the two HP4600s have had no problems with the printers since then. Stick that in the filing cabinet of your mind under "Who'da guessed". Thanks for all the help...