Im getting unable to print 50 error on my brother mfc 665cw

Try this Brother MFC 665CW Unable To Print 51 Error Solved

in my printer brother mfc-7340 when i coping with machine after some time display will show print unable with error code 72 what i will do? plse tell me;

1. Clean all feed wheels and guides with methylated spirits.
2. Look for any switch or guide that may be bent or out of place. This could have been damaged when a jam was removed.
3. Look for any small piece of paper or staple that may have lodged in the paper path somewhere.
4. Ensure the paper is dry. Not stored in a cupboard in the kitchen or the printer is not setup infront of an air vent.

51 error says that the purge assembly is stuck and not cycling properly. If you can power up and get the printhead to the center and unplug again, look with a flashlight in the far right corner where the printhead parks for any paper scraps or things that don't belong and remove them it might work again. Otherwise a shop repair to possibly replace the cleaning assembly.

the encoder strip is probably out of its socket. its a long mylar strip that goes from one side to the other, and goes underneath the printhead.

Did you have a paper jam before this happened? If yes then the paper must have pushed the encoder strip out of alignment. You will need to turn off the printer and then push it back into slot to fix it. Let me know if you need more help. Sai.

unable to print 50& 30

Normal 0 I suggest you get a sheet of Card Stock (Heavy paper) and place it in the feed way. Then press the print button applying a slight amount of pressure on the Card Stock so it will feed through the printer. The reason for this is in some cases I have been able to clear the paper track of debris that was deposited there over time.
Worth a try, as I have fixed a number of printers this way, saving costly repairs.
Hope this helps. Bud

...and 50? Is it toggling between those two error codes?

Anyway, see here what to do:
http://www.fixya.com/support/t211210-brother_mfc845cw

same issue:
http://www.fixya.com/support/t294185-brother_mfc_240c_change_unable_50