Auto Parts: Brake Booster Toyota Camry 2001, toyota camry 2001, toyota camry

Question
I replaced one with a salvage yard one about 6 mo's ago, at 158K miles ...($150 for parts and labor vs $1200 the dealer wanted).
The replacement seems to have gone out already at 166K miles . Please advise as to what might be causing this  part to go out.  

Answer
    If you just replaced the booster, and used your old master cylinder, then I know what's wrong.  The back of the master cylinder is leaking brake fluid (and it doesn't take much) into the booster and destroying the booster's diaphragm.  Next time, get both pieces together and check them thoroughly before you decide the repair is finished.  If you buy one that leaks, most yards will replace it.