1st garage installs new alternator. 2nd garage installs catalytic convertor about 4 days later, claims to hear alternator making grinding noise and sparks so part is bad and 1st garage should replace. 1st garage points to marks and says that 2nd garage damaged part. 2nd garage says tapped on it to see if that would make noise go away. Only slight scratch marks visible on alternator. Was it bad to begin with or damaged by 2nd garage?
Col. Mustard in the library with a lead pipe.
I’m sure there was a reason to use shop #1 and shop #2 four days apart, but this who dunnit would be difficult even if it wasn’t over the world wide web. Sorry.