How to troubleshoot unexpected output or failures in Awk scripts?

When an Awk script produces unexpected output or fails, I need to diagnose the root cause without altering the script’s production logic. I have a Unix‑like terminal, the script file, and a sample data file available. I am unsure how to effectively verify field delimiters, insert non‑intrusive debug output, isolate problematic records with a reduced dataset, and confirm that pattern‑matching conditions are correct. What systematic approach can I use to troubleshoot Awk script failures while keeping the original script intact?