asked May 17, 2008 at 3:43pm
Hp HP LaserJet 4M

HP4M post repair jam

Installed fuser gear Moe recommended/provided to correct the free spinning fuser and rubber roller problem in an HP4M. Excellent diagnosis, excellent instruction, installation went fine, fuser roller and rubber roller now turn with the gears. Installed Exit Jam Kit to replace the original equipment. Excellent instructions again.

But I must have missed a step or mis-installed the repair parts. Problem: the printer initiates printing, deposits toner on the page, starts paper through the fuser assembly, but paper only gets 1" out of fuser assembly and stops – "13 Paper Jam" display. After opening and closing the toner cartridge door and pressing "On Line", "jammed" page cycles through rest of path and out, but printer tries to reprint jammed page and jams again in the same spot, and the cycle starts all over again.

Any ideas what I may have missed in the repair? Thanks.
Check the exit sensor arm in this photo
It could have broken where it attaches to the peg when you removed or reinstalled the fuser.
by moe on May 17, 2008 at 6:09pm Add comment
Thanks for the photo link. Spring (bottom pics) is okay. Problem must be in the exit sensor arm. It's still in one piece with the paper sensor end attached to the switch "flag" at the other end. But...there seems to be a lot of play in the arm, too much. It does not rotate on its axis evenly. The exit sensor arm can tilt rotate (yaw) out of the way as paper passes by and not move the sensor flag much/enough to push the flag into the switch receiver in the exit assembly.

In my repair just opened the end to change fuser gear, not a full Fuser Repair Kit and didn't take the fuser top off, so don't know exactly what exit sensor arm should look like.

Does the top pic show metal parts around the shaft of the exit sensor arm assembly shining through oval opening in the top of the fuser? The exit sensor arm/assembly on my HP4M is all plastic, no metal anywhere around it except for fuser top and frame.

Is the exit sensor arm held in place by anything (clips, springs, etc) other than where it emerges from the fuser assembly on the right hand side (from fuser back). In video exit sensor arm seems to be stable as the Separation Guide Assembly is removed. No clips or springs on mine. I think it would drop out if I removed the Separation Guide Assembly.

Should left side (from fuser back) of exit sensor arm shaft or end seat (this what you mean by peg?) somehow in the fuser assembly to keep axis rotation true? Mine does not and this is where there seems to be too much play.

Maybe broke something, but don't know what. Do you have parts or a repair kit for this?
by chris_alt on May 18, 2008 at 2:07pm Add comment
You can take the fuser apart with the use of the video you got. The part you'll need is the fuser guide plate. That's the part with the yellow label on it. The end of the arm has a cup that sits on a plastic peg. It's this plastic peg that breaks off, allowing the arm to wobble. If you need the guide plate, we have them in stock. Click on my name to email me for pricing/ordering info.
by moe on May 18, 2008 at 2:22pm Add comment