Jobs at small Denver companies nobody posts about - 3 months and counting

A friend who works at a local manufacturer says there are openings not advertised online. I am in Denver, in case local advice matters. They like a brief email with a résumé. Should I visit in person?

Keep a list of who you contacted and when. It makes follow-ups easy.

Visiting in person worked for a trades job. For office jobs, email was better.