I am working on an 83 Shadow 750. I cleaned the carb and replaced the boots. It is acting like it’s pulling a major air leak and the only place I have found a leak seems to be around the boot. After combing through the shop manual I found this reference to an O-ring in the insulator. This is the only reference I’ve found to this O-ring and I can’t find it in the parts diagram. It would make sense to cause an air leak but I wanted to see if anyone has some info to point me in the right direction. The manual covers 83-85 so it’s possible this wasn’t part of the 83. For context, the carb is moving smoothly and clean, the throttle cable is free and not hanging up, there are no vacuum lines on the carb, just a vent to atmosphere. Any help is appreciated.