@ hiendmmoe
Another vote for the Herbie’s tube dampers.
I purchased several pairs of the Herbie’s HAL O dampers back in 2005. I use them on 6922 signal tubes. The Herbie’s still look like new to this day. (Tubes are various manufacturers pairs of early to middle 1960s 6922/E88CC and 7308/E188CC tubes.)
As for placement of the Herbie’s on the tube. I first installed them where the general consensus, back then, was to install tube dampers at the top mica support or slightly above. I like you found it sucked some of the air/life from the music. I then experimented adjusting the placement of the Herbie’s on the glass envelope of the tube. The best place I found, for me, my system, was at the of the tube just before the fold of the tube.
Jim