Hibred Z

Hibred Z wants to thank you for your help

after removing the above mentioned valve from my firewall and unable to find a replacement or a rebuild kit, I decided to take it apart and clean. I notice after removing the top bolt head it is connected to a machined internal part that has a grove cut into it and inside the grove their is a drilled hole through the shaft. To me it looks like a rubber O-ring fits into this grove, does anyone know if an O-ring is needed.