ALL MODIFICATIONS ARE DONE AT YOUR OWN RISK!
*Not recommended for PCB constructed amplifiers.*
Here are the parts you need for this modification:
Spring Tube Retainers
https://tubedepot.com/products/retainer-for-el34-6ca7-6l6?utm_source=google&utm_medium=cpc&adpos=&scid=scplpSK-RET2&sc_intid=SK-RET2&gclid=CjwKCAjwiuuRBhBvEiwAFXKaNBU1G-iX7Cfj8HznW_asKAFlX1Fmg0ysMW2DlSkW3lJC-IXtfuw6whoCC50QAvD_BwE
Silicon Tube Damper Rings
https://www.amplifiedparts.com/products/damper-rings-high-temperature-silicone-red
½” x 4-40 screws
https://www.homedepot.com/p/Everbilt-4-40-x-1-2-in-Phillips-Round-Head-Machine-Screws-61078/203091609
(optional) Silicon glue is recommended for securing the ring to the inside of the spring retainer.