I've recently acquired a used '09 Japanese manufactured Fender Jaguar Bass from the original owner. I wanted to make a neck adjustment, but when I tried to use the hex adjustment key, I could not find anything that fit it at the top of the neck. There's a hole there with a black liner, but the usual chrome nut isn't evident. It seems to be kind of a deep pocket. Does anyone have a similar model, and can shed some light on how to adjust the neck?