Thanks for the feedback and sorry to hear you aren't seeing birds on your finch feeder! FYI, there has been a trend for bird seed producers to 'overcook' the nyjer seed during the process to sterilize it/keep it from germinating. When really dried out, the finches may refuse to eat it. I'm not sure where your current finch seed came from, but this might be the issue.
Same goes if the nyjer seed sits and gets moldy. Does this feeder get hit by your or a neighbor's sprinkler system? Has it been sitting stagnant for more than a week? If so, the seed will cake and become moldy, and the birds won't touch it. Best thing to do is clean and dry it thoroughly, put in fresh seed, and move to a dry location in your yard. I carry a feeder fresh product to help with seed molding issues (https://nature-niche.com/products/feeder-fresh), but I'm not convinced it will help a feeder that sits within a sprinkler's daily spray path.
Hope these suggestions help!