LJ 4345 with sporadic jam error 13.20.00

[hp_rocks]

I have a severe problem with a LJ4345 MFP.
The printer jams sporadic and jam error 13.20.00 appears.
(Error Code List says Jam because of delayed output of the paper)
Then you open the printer and a sheet of paper is under the toner
cartridge, this means the leading edge of the paper hasn't entered the fusing unit
but is directly at the fusing rollers and the trailing edge of the paper has already
left the rollers of the registration assy. And approximately the  last third of the sheet
has Z-shaped wrinkles and stucks under the black flap of the registration assy.
So you can take the sheet out of the printer without pulling it out of the fusing
or registration rollers.
The interesting thing is that the paper is blank,  there is no toner and print on it.
The jam occurs very rarely. I printed 1000 test pages with the internal paperpath test
of the printer and it occured two times.
I first  printed  500 test pages straightly without a jam. Then i used the sensor test together
with the paper path test,
where the printer prints 10 pages then stops and prints another 10. Then  the jam
occured. The Customer said to me thats it's possible to print 100's of pages without
a jam and then the jam occurs 5 times when you want to print  10 pages for example.
I don't know if this is all by accident.
I have already replaced the fusing unit, the pickup and separation rollers of paper tray
2 and 3 (so 6 rollers together) and i have replaced the feeder assembly RM1-0012-020CN  behind tray 1.
(the sensor of it works correctly)
Don't know if it would be wise to replace the top of page sensor (PS103) and the two paper width sensors
beside. (Lot of work).
The firmware version of the printer is the same of the other ones of the customer which work fine.
So I don't think its a firmware problem.
The printer has a stapler/stacker output unit.
Perpaps there's an expierenced technician out there who could help me.

Thank you very much.

[davidzuts]

Probable cause is the registration sensor being dirty. Remove all the screws that secure the registration assembly inside the toner cavity and then gently lift the unit on the left side and use a can of compress air to blow at the center where the sensor flag is located.

[hp_rocks]

Thank you very much for your answer.

I've already blown out the sensor.

(You can't really see the  photo sensor itself).

So my next step is to replace the sensor/sensors

(top of page and both paper width sensors).

But it seems you can't order these parts.

I've found no part numbers on partsurfer or elsewhere.

I've demounted the parts from an old 4345 which is out of use.

(Quite a lot of work).

But I wanted to ask here if it's true that you can't order these

parts (the sensors separately or the whole frame where they are mounted to)

as new parts before i use my old ones.

Thank you very much.

[kevin_adams]

I was wondering similar to David on the registration assembly.

The normal cause of 13.20 is the flag in the feeder rollers but you only get a couple of jams in perhaps 1000 sheets.

The crumpled media suggests its still being fed from behind so the printer does not know it has reached the point, it's still being driven so hits the registration, is not detected and is driven more, possibly forcing through the reg ?

It then times out and the sensor is still obscured so perhaps the 13.20 is not accurate in this case but the printer making a best guess?

Is it possible the tip of the registration flag has worn or come off ?

If you have the luxury of an old unit nearby you might find removing the registration and a visual inspection worthwhile just to double check.

I'd even wonder about trying the registration from the old unit just to eliminate it ?

[davidzuts]

The other item to check is the solenoid that controls the release of the pickup roller as over time the dampening material tends to wear and the glue that held it sometimes makes the "L" arm stick. This would be an issue if it only happens from one of the trays.