What causes doctor blade failure?

[Compman55]

These are for the C LJ 4650 printer.

On my C,M,K cartridges, I was able to diagnose that only the doctor blades had failed. It was leaving streaks of "less deep" toner throughout the developer roller. One developer roller on the (K) cartridge had some deep gouges from prior damage, but on the other cartriges the rollers were fine. So, what typically causes these to fail?

[redcow]

Doctor Blade was a new one for me.
I checked the service manual and nothing.
I then checked the 4600 PQ Defects Guide and there it is.

Under possible causes:-
Caused by the vibration and pressure of the doctor blade against the developing roller during shipment/storage of the cartridge. The vibration and pressure cause a narrow indentation across the developing roller. As the indentation rotates around to the OPC, a darker band of toner is developed onto the OPC, then onto the media.

[Compman55]

However these defects are verticle lines of no toner. Like a developer not being charged evenly. Not stray lines, but maybe "grain" lines if you will.

Too bad I can;t get my scan size down or I could upload a pic.

[cs_steve]

There are a number of factors that can cause for a Doctor Blade failure on toner cartridges.
If the blade has been used more than one cycle.
If the mix of the toner components are not correct.
If the Developer roller has wrinkles on it and it has been cleaned with the wrong cleaner solution.
If the toner is OEM. then it depends on how long the toner sat on the shelf. Most toner cartridges new or remanufacture have a shelf life of 1 year and if you go over that specially on sensitive toners such as color toners this can cause a quicker failure to internal parts due to toner getting clumpy and too dry.