HP Color Laserjet Enterprise M750 printing grey horizontal lines

[CJLANDRY]

Hello, 

I replaced the transfer kit at the end of July because I was getting horizontal lines printed especially near the bottom of pages, but some also in the middle.  After replacing the transfer kit it worked great and there were no more lines until today.  The "Pages since last transfer and maintenance" are 45,800.  I am wondering what I need to do ?.  Do I request a replacement transfer belt ?. Or should I be cleaning the belt, wiping it off ?.  Should I be trying to "empty the reservoir" at the end of the transfer belt ?, or could it be that the toner collection unit needs replacing ?.   I really don't know where to start.  My inclination is to call and ask for a replacement for the transfer kit that I bought at the end of July.  The odd thing is that when I replaced the kit at the end of July I was sent an HP kit that was defective and had to request a replacement at that time. This is frustrating because I need to be printing up documents on it, and need to depend upon it.  Any help is appreciated.

[Alex-TATS · Accepted solution]

Hi CJLANDRY,

Firstly, are you using genuine HP toner cartridges ?

Assuming that they are ...

Things to check/do:

1) Check the TCU (toner collection unit) if it is full. In this case it will need to be replaced.

2) Check the ITB (intermediatte transfer belt) toner waste compartment for any excess of toner and/or various bits of waste

     Clean that compartment, ideally with a toner vacuum

3) Print some paper path test pages, let's say 20 and see if the issue disappears or gets any better

I hope these may help,

Cheers!

[CJLANDRY]

Thanks for the quick reply, I will give this a try.  To vacuum the toner waste compartment, will a shop vac do ?.  I don't own a toner vac and they look really expensive.

Thanks again

[Alex-TATS]

No, normal home use vacuums won't do, avoid that. Better clean then with a brush, carefully though in a plastic bag. This can be very messy though. 

[CJLANDRY]

Hello, 

So I cleaned out the "collection bin" at the end of the transfer belt and it seems to work fine now, thank you !.  But at the end of a print job there is a screeching noise for 8 seconds or so as the printer cycles down.  Would you have any ideas what this might be and how to fix it ?.   Thank you !

[Repairatrooper]

Not sure what the screeching noise would be but I have a suggestion to reduce the need to empty the waste bin on the belt. 

1. Make sure that your firmware is up to date. There were changes made to help prevent this situation.

2. Ensure that the printer is either completely level front to back or that the back is slightly lower than the front of the printer. This helps to ensure that toner flows back to the waste bottle instead of staying in the bin. Use a level to check this, do not eyeball it.

[CJLANDRY]

OK.  I believe the firmware is up to date, so that's good. I took a level out and notice that from front to back it seems perfectly level, but from left to right the printer is currently high on the left side by about 1/8th of an inch.  I am going to try your suggestion of elevating the front end by maybe 1/4 of an inch, even out the left to right level and see if this makes a difference.

Thanks for your good suggestions.