While re-installing the tach, I discovered a loose wire with a connector and seemingly no place to go. In the dim light under the dash. the wire appeared to be brown, but that could have been age. (either the wire's or my eyes') The grommet fit the threaded mounting stud on the back of the tach perfectly. I assumed it was a ground wire and put it on. However, it has bugged me ever since. Is there supposed to be a ground wire on the back of the tach? Everything seems to work. (Flash to pass has never been connected.)