When you've tried all the recommended glue/epoxy to make the insulator stay and you're still having problems, try looking at your endpoint settings on your throttle servo as well. This is a common problem I've seen a number of times. The throttle servo (especially when you have one of the better ones) actually pulls the carburetor when the throw more than what it's supposed to. Check to see if your endpoint is set right. It should open the carb all the way but that's it. Any more beyond this point can pull the carb. Same thing with the brakes. If it's way too much, the servo can also bend the idle screw (but that's a whole another issue).