Jobs at small Detroit companies nobody posts about - what worked for you?

Two small Detroit employers told me they are hiring but have not posted yet. It has been weighing on me all week. One is a print shop, one is an accounting firm and one is a clinic. Should I visit in person?

Thanks for writing this out. I went through something close to it 5 months ago, and it got easier once I kept a simple log of every call and form.