Tube location info: The Gold Pin ECC83S replaces the 12AX7.Combo amps are very hard on tubes because of vibrations which can cause tube rattle with any brand of tube. If you play by yourself in a quiet environment or record with your amp you may want to consider using the EuroDamper tube damper rings for the 6V6S and the 5Y3S. These are available in the "Related Products” tab as a set of two and will greatly decrease tube rattle.