tubes going microphonic always same channel???

I have been having problems with mullard 12AU7 57 sqaure getters going microphonic on me. It's always the same channel, the outside tube close to the chassis. Is it because the pseaker is close (2.5') to that tube (see my system to see how speakers are placed).

Never really noticed this problem until I put in the square getter pre 58 mullards. I love the sound of these tubes, they are in a Cary CD 303/300 CD player. I'll put the 58 halo's in or some amperex to see what they do, or what is causing this. Hate to waste good tubes.

The tubes aren't cheap and this is the thrird one to do this in the same socket. I have done some tube rolling, hope the socket isn't bad. I'm a electronic tech, and my dad is a old tube tech from way back. He says it's because they are old junk tubes..LOL Just odd it's always the same socket??

Is this just a problem with old used square plates?? Are they more sensitive?? You can really hear it when the CD drawer opens. Then they will start making noise. I pull them out when I hear them, as it means the tube is bad.

Any opinions or help would be great.

Scott