Just to add to this, you not only have to be National or higher, you also have to compete the graders course. Graders are also 100% volunteer, and it takes a LONG time to grade a full set of exams, so eligible graders can’t just take exam set after exam set and still have a ’balanced’ work life.
If you know someone who is National or above that is NOT yet a grader, please encourage them to sign up. And if you are looking to take the exam, please look on the BJCP site for the grading rubric, so you know what the graders are looking for specifically before you take the test.
Cheers.