Can someone confirm for me what is the correct size allen wrench to use for adjusting the truss rod on a 78 Fender Jazz bass? On mine, the 9/64th wrench seems too big and 1/8 fits loosely in the nut. I assume the allen wrench should fit snugly in the nut. I have confirmed the nut is not stripped. I want to proceed cautiously with this as it is my first truss rod adjustment. Thanks.