Jobs at small Columbus companies nobody posts about - first time posting

A friend who works at a local manufacturer says there are openings not advertised online. I have read a lot of threads here and could not find my exact situation. They like a brief email with a résumé. Should I visit in person?

Small employers often hire on recommendation. Ask neighbours, former co-workers and your library.

A short email with two sentences about what you can do and your résumé attached worked for me. I followed up after a week.