I had a 1st release back in 2015 with the same issue the only way i could fix it was to remove the peg from the head (using a hair dryer) then heat the neck carefully then while the neck is soft put the peg in and then pinch it using all 4 fingers to push it tighter around the peg and cool it using cold water. It worked but you have to be careful not to push on or mishape the collar because the black paint gets soft enough to make it stick to the neck and or cause paint rub and you have to reheat it to “reset” the collar to its position and that can cause the neck to reset and be loose again. It worked when I did it but honestly I sold it as fodder and bought a few more which didn’t have the issue.