I have been refilling these cartridges for  over three years without problem.  I had a large supply of ink left over from when I was filling Epson cartridges 3 years ago.  I bought a new set of refill inks as I figured the old ink was probably not good for the Brother print heads, though I wasn't having any problems.  I suspect this new ink is now causing me problems with the black.  It started printing faint (gray).  I have done several head cleanings and it has improved some, but still not real dark.  Anybody know enough about ink to advise me of a good place to buy quality ink in small quantities?  All the sellers say their ink is top quality of course.  ????
			
			