Slave cylinder

[1eightySX]

So, like a month and a half ago my slave cylinder on my 91 180sx called it quits. It was a sunday and the dealership was not open so I headed down to my local part store and bought one. Installed it and it worked, however today the same symtoms re appeared. Now I am wondering, could there be something else wrong with my car or is it just that the aftermarket replacements are crap? I remember the first time i searched somone mentioned that the aftermarket ones are no good, that is why i ask.