Hi, 
I dropped my son off at school this a.m. and his teacher was upset.  He has a '93 Legacy. He had the timing belt changed in January and now the crankshaft pulley key "broke".  He was quoted $500 for repair by the shop that did the original timing belt change.  I suspect that the shop failed to adequately tighten the crankshaft bolt back in January.  So my question is how should he proceed?  Is it customary for a shop to warrant their work?  Is it possible the key broke just coincidentally?