Deep30

The wrong Allen key can cause a bit of a problem. Too small can strip it and too large won't go deep enough and just spin. The correct size goes deep into that tube. These BBP basses also have dual-action truss rods. There is a neutral "dead zone " when going from straightening the neck clockwise to adding relief going counter- clockwise. It will feel loose and then tighten up as you add relief. It can be scary when some people hit that loose zone.