Horizontal lines in prints C75

[positiveg]

Please take a look at prints made and also drum test
We had the tech Ce in do some ori t's etc. We ran about 15000.prints of a form but was mainly black ink, last two days. And because was forms was all letters no graphics but a all logo at the top. We experienced nothing like this. Yesterday now we noticed this in the prints
They seem very consistent.
Don't want to believe it may be the lasers because then why on all the pro t's and about se level of consistency between each line et

Please assist thanks

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[positiveg]

Ok the issue seemed to have been bad black toner.
I peeped at the black developer it was good.
Then remembers put in a black toner that got out of a sale from a seller.bad choice they really messed so now I'm getting better prints but I need to know why this is happening

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[positiveg]

The lines are back. I'm not sure if the faulty black toner has completely run through the system. Which I thought it had or what but take a look at the prints the lines

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[Detonation]

What's the repeating distance of these bands?

[positiveg]

What's the repeating distance of these bands?

approx 1 cm

[Eremite]

Chek the gear in second transfer roll.
When the machine is printing, do you hear abnormal noise?

[positiveg]

Well I changed the developing unit in the black. Just say got a few good prints then back to normal follows by a grinding sound like it's coming from the back of the machine. Like gears. The 2nd BTE just messy. But I think that's from the magenta developing unit cover plastic strip being burst off so we installing a new one tomorrow. But that grinding sound happened before we change the waste toner unit ans now it's back I don't know this printer is causing more harm than good right now

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[Milo Wilson]

Rear waste auger is bound up. Backing up all the developers.

[positiveg]

Rear waste auger is bound up. Backing up all the developers.

Strange I bough the entire unit for HST. And some other parts like leveler for hat area.
This thing giving more issues.
But would it cause the lines in the prints or just the lines?

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[positiveg]

Ok I pulled the waste toner cartridge and like you could tell it was backed up. So I emptied it. The noise is gone.
But the prints well the lines are more widely spaced a little over an inch, apart.
I'm so lost right now. As what we though was giving the issue a bad black toner now we jus not getting the correct colours one an and the lines

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