If I pass some but not all sections of the interpreter test, do I have to take the ones I passed again to reach a higher classification?

Except for conditionally-approved interpreters who have not retested within the two-year timeframe (see Note #2 above in the Fail: Conditionally Approved subsection of #1 above for details), once a candidate has passed a section of a test at the Master level, that candidate does not have to take that section again. For example, if a candidate scores at the Master level on the sight section, but below the Master level on the consecutive and simultaneous sections and wishes to be retested in the hopes of reaching the Master level, that person will have to retake only the consecutive and simultaneous sections.