Good question, I've replaced mine twice with 116k miles on it now. I bought the NAPA box and had a lifetime warranty so the second time didn't cost me anything. I'm not sure if the first replacement went bad because of the way it was built or a really small adjustment I made but the second has been fine and it's not some super high end version. Mayabe you just got a bad box...it does happen now and then. I'd say try making a very small adjustment and worse case you get another that should be normal.