Bizhub pro 1051 backgrounding/scumming issue

[cmitchprint]

Our service was just cancelled after 10 long years. Machine has been great the last 8 after earlier issues were addressed. Lately, we've been having a scumming/backgrounding issue with some toner pickup happening smack in the middle of sheet. That appears to be cleaning blades since that was what always cleared up the lines appearing on the sheet. however, the backgrounding over entire sheet (looks like press scum all over) is steadily getting worse to the point we can no longer run it. Charge corona is new, transfer belt is new, developer is new, drum has about 90,000 on it. Any ideas where I need to look. I admit I am new to service on this machine so I'm sure I'll get in the groove once I am aware of what to do. Attached is a pic of what I am talking about:

 

[cmitchprint]

Cleaned toner density sensor below drum and vacuumed out machine. It is greatly improved but get this, it is lightly toning on just side 2, Side one is clean as a pin.

 

[The Copy Guys]

Developer/developer unit fatigued. Also, the cleaning input shaft can get worn causing a loss of ground to the cleaner brush. This does not look like a failed cleaning blade.

 

[cmitchprint]

The developer UNIT appears to be original to the machine. The developer is new. Less than 100,000 on it. So, you say change out developer unit? The service of cleaning up machine and sensor and recalibrating helped for a few days. Now it is right back where it was.

 

[The Copy Guys]

The developer UNIT appears to be original to the machine. The developer is new. Less than 100,000 on it. So, you say change out developer unit? The service of cleaning up machine and sensor and recalibrating helped for a few days. Now it is right back where it was.

Sorry for the delayed reply. Yes, replace the dev unit. After several million impressions the mag roller can get too smooth to properly control the flow of developer over it. Also conductivity for the developer bias can lesson causing a lot of toner misting.