I suggest that you tune your autoharp with a digital tuner that will give a readout in cents. if you don't know about cents then your probably tuning to 12 tone equal temperament!
confused? then I suggest that you read and study a type of tuning called JUST intonation or otherwise known as pure tuning,you will enter into a new world of sound. very briefly a much more melodic sound is produced using this type of temperament amongst others. some notes are tuned flat by as much as say 12cents, while others are tuned sharp by as much as say 6cents.
ok you may want to know what particular values in cents are required for each note.
ANSWER go to a website on JUST INTONATION by KYLE GANN its an eye/ear opener.
you don't know what your missing.
hope this helps, best of luck denj.jones@tiscali.co.uk