When Harry changed from 12.6 to 12.7 he brought back adjustable fluid damping. IMHE it was a big improvement and continues to be useful. What I hear contradicts @stringreen 's comment above about closing in the sound and eliminating air. That's what happens when it's OVER-damped, not damped. If that is your result, just dip a Qtip or two into the fluid to absorb a bit of oil and you should be good to go. Cheers,
Spencer