What causes a light band on a laser printer?

[MTAX]

My Lexmark Optra S prints an annoying light band that is constistent on all the pages. Is this a drum or toner problem? I'm using generic toner.

 

[vexingv]

its the toner...a printer at my school's lab has the same problem and the error display on the printer lcd is "low toner"

 

[MTAX]

My toner cartridge is almost new. I increased the print darkness to max, the banding is not as prominent, but still visible. I'm suspecting that the cheapo refill toner cartridge is the cause. Original lexmark toner is real expensive.

 

[dullard]

It could be a couple of problems. Here are some that I've commonly seen:
1) Something blocking the toner from getting to the paper (an object or some dust).
2) A scratch/object on the bluish roll that receives the electric charge.
3) Toner isn't properly distributed. Just take the toner out and slowly rock it back and forth 180°. Or if you are lazy, just tip the printer back and forth 180° a few times.

#3 is the most common.

 

[dkozloski]

Is the banding in the same direction the paper feeds or is it across the direction of feed? If it is across the direction of feed it may be something has scuffed the silicon drum. If it is in the direction of feed the toner needs to be distributed in the cartridge or there may be a piece of paper, tape, or other garbage inside it. Third there may be a scrap of paper floating around inside the machine.