Help with Tube Designation on the Cary Audio 120S


I need some assistance from an experienced Cary Audio 120s amp owners! I am experiencing a high pitch ringing sound coming from my speakers after listening to music for a couple of hours or more. I have some Brimar and Pope tubes that I rolled into the amp recently. I am trying to pinpoint if I am dealing with a bad tube or if I have the 6sn7 tubes meant for the driver stage (Brimer) in the input stage (Popes). Could someone please confirm for me the location of the driver inputs versus the input stage on the Cary 120s? It doesn't have this info in the manual for the amp. Thanks in advance for your help.
houstonjazzfan
Thanks Pescolar,

I have tried the tapping of the tubes... unfortunately, I have not been able to identify the culprit. I will see if there is any place I can test the tubes locally.
HAVE SOMEONE TO CHECK THOSE TUBES THRU A TUBE TESTER..POSSIBILITY OF A MICROPHONIC TUBES?
BTW,TRY TO TAP THOSE TUBES BARELY WITH YOUR FINGER AND CAREFULLY AND HEAR ANYTHING FROM THE SPEAKER...WHEN TAPPING AND YOU CAN HEAR IT FROM YOUR SPEAKER THEN IT IS A MICROPHONIC TUBES. ( NO CD PLAYING).
I HOPE THIS HELP.
PESCOLAR