little black arm/hinge on door??

[jeff69dini]

ok, funny question, does anyone know what the official name of that part is? its the little black plastic arm on the back doors that functions like a sliding hinge, guess prevents door from opening all the way or something

strange thing is that yesterday I tried to open one of the back doors and it just stopped half way, it was greased and stuff, now it seems like its grinding on something opening and closing, how does this thing work? it slides inside the door, is it a simple thing or does it have bearings? etc

thanks