First, super, then unfortunately only flawed

We bought the cartridges for our Brother printers in the office, that is, we print quite a lot. The first 3 black cartridge ran smoothly, the printer result was great, as with the original cartridges. 4. With the black cartridge unfortunately began etrem streaky printouts. First half cleaning, then 2 cleanings, eventually helped even more nichs. I now clean the printhead from the printer several times during the piece let (4 times!) And remains the poor result. I will make myself now fast on the way to other cartridges in the hope that the problem will disappear. The printer was actually new.
I can not recommend unfortunately.