hey.
just did mine today!
the best way i have found of diagnosing it is drive it about 40 or where ya can hear the whine really well. them turn really sharp left and right.
Gf it get loader and quieter ya can tell which side it is.
louder when ya turn right then its the left and Then its vice versa

hope that makes sense!
chris. may as well get new with your discs mate.
ya need to do them anyway!
ya can lack the car up and turn it to see if it grinds or anything as it turns. and do the wobble thing.
but i had a cracked race today. and the wobble thing didn't detect that

hope that helps:)