What systematic debugging techniques for elusive production bugs in Java?

[EleanorT]

I'm a junior software developer working on a large legacy codebase written in Java, and I'm consistently spending what feels like an excessive amount of time trying to track down the root cause of intermittent bugs that don't produce clear stack traces or log messages. My current debugging techniques mostly involve adding print statements and stepping through code in my IDE, but this is inefficient for complex issues involving concurrency or interactions with external services. For experienced developers, what systematic debugging approaches or tools do you rely on when faced with a particularly elusive bug? How do you effectively narrow down the problem space in a large system, and are there specific strategies for debugging issues that only appear in production environments where you can't use an interactive debugger?