HP Laserjet 4345 (old beast) Intermittent Jamming at Drum/Toner unit

**Doug James** · 01-01-2023

Hello, This machine actually looks in great shape. Jams on large copy/print jobs right at the drum unit. The paper will "crunch up" right at the drum unit. I tried an OEM drum and that turned out not the problem. (Customer had it and swore was brand new although thought couldn't get those anymore). Also tried several reman drums. Out of ideas at this point other than main drive assembly. Any thoughts would be helpful THANKS SO MUCH !!!

**JR2ALTA** · 01-01-2023

Originally Posted by Doug James

Hello, This machine actually looks in great shape. Jams on large copy/print jobs right at the drum unit. The paper will "crunch up" right at the drum unit. I tried an OEM drum and that turned out not the problem. (Customer had it and swore was brand new although thought couldn't get those anymore). Also tried several reman drums. Out of ideas at this point other than main drive assembly. Any thoughts would be helpful THANKS SO MUCH !!!

registration units have that metal swing plate that stick on gummy pads. clean off with alcohol. there are also registration clutch(es) that can be replaced.

**subaro** · 01-02-2023

In the day I repaired quite a number of those. When they worked good, they are great, but when they give trouble they can be very frustrating, especially with hp mystery jam codes.

The registration rollers get cake dirt on them and has to be cleaned and the bushing lube with a bit drop of oil. There is a actuator just at the front of the bypass feeder that sticks and causes jams, it's called the pre feed sensor. You have to remove the covers and the bypass and service the area around there. Also check that the tray rollers are in decent shape. you can get the pdf service manuals on the net, do a search. Also is should throw a jam code, what is it.

Also pay attention to where each type of screws are removed, as things can get messed up by putting the wrong screws in the wrong place.

**i-have-fax-problems** · 01-11-2023

Originally Posted by Doug James

Hello, This machine actually looks in great shape. Jams on large copy/print jobs right at the drum unit. The paper will "crunch up" right at the drum unit. I tried an OEM drum and that turned out not the problem. (Customer had it and swore was brand new although thought couldn't get those anymore). Also tried several reman drums. Out of ideas at this point other than main drive assembly. Any thoughts would be helpful THANKS SO MUCH !!!

I had this some years back. Cause was the toner unit (non original HP) itself (sluggishness I guess)

**Doug James** · 01-12-2023

I sure do appreciate all the responses. I changed the whole gear assembly and changed to another image unit. Got it to run 150 copies with no jams. I really think it was a compatible drum issue. And just old age. Not to mention cheap paper. So far so good THANKS AGAIN !!!!