Best protractor for aligning to cantilever


I am trying to find a protractor that makes it easy to align the cantilever rather than the body to a grid. I have a cartridge where the cantilever is not perfectly parallel with the body. It's a Grado and the plastic on the front of the body is not seated correctly or something. The cantilever is parallel to the back, but the front being out of alignment makes it hard to align to the body. It is merely a cosmetic issue so I would like to keep the cartridge.
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I just got word that a mint lp was shipped to me from Hong Kong yesterday. It's for a Linn Sondek 12 w/ a Basik tonearm. Since Linn tonearms are the same length, I can upgrade and still use the tractor.
Polk432 -- Yip at mintlp is quite helpful and has me researching the subject at informative sites before I use his services. I have one well-documented vintage arm and a rare, undocumented one, so this should get interesting. Thanks!