After refilling the print quality is very poor

hello you have to update your firmware. www.youtube.com samsung ml 1640 toner reset

hello relace new toner

try cleaning the internal top part of the printer... if the toner or dust is covering the laser unit.. you will have print out distortion.. like blur print out..
how many copies have you printed with the printer? toner that comes with the new printer is normally less than those replacement toner which you buy later..

See if there is something in Printer Preferences or anything like that. See if there is something that says the printer will with low quality.

Dear sir,

1. open your printer cartridge drum cleaning blade unite wast toner clean.
2. open two side from your cartridge left side and right side
3. open plastic cork
4. filling toner
5. assembling again
6. start print

Full isn't always the answer, in order to refill a cartridge properly you need to also replace the cleaning blade inside. The blade wears out and doesn't clean the drum properly and also lets toner leak all over. Your best bet is a new OEM cartridge, or put a new cleaning and Dr. blade in yours.

i have refil this cartridge printer is not recoganised

You need a refill kit with a reset chipfrom CartridgeCo UK www.cartridgeco.co.uk tel.0845 388 3576

Download the firmware from here http://org.downloadcenter.samsung.com/downloadfile/ContentsFile.aspx?CDSite=in&CttFileID=2238869&CDCttType=FM&ModelType=N&ModelName=ML-1640&VPath=FM/200904/20090416100856890/ML-1640_V1.01.00.83.exe
run the software and this will reset the page count to 0. Samsung printers generally do not support a refilled cartridge and thus the red light.But resetting the page count to 0 makes the printer detect the cartridge as an intoductory one.

Usually indicates poor toner. Have you had your toner replaced recently. Refilled toners are notorious for this.
I have had this problem before....replaced toners with a good supplier or manufacturer. Problem solved.