Hi,
Yesterday, I got a laser printer Samsung ML-1640 with this problem:

http://img844.imageshack.us/img844/2695/vzv.png

The interval is 75 mm which points to the the drum (diameter of 24 mm).
Last year I had the very same problem with another ML-1640 which I fixed
by inserting a refilled and tested drum-toner-cartridge from Ebay.
Does anyone here have an idea what the cause of this problem could be?
The cartridge can be disassembled to the last piece which I did once
without finding anything suspicious.

Thanks in advance
Jens