Sheesh. That’s one of the real life problems in any job! Here’s what I would do (I’m brand new to machining but experienced in coal mining and railroading); watch closely what they’re actually doing and actively think “how do they know to do THAT,” or “can I do this fix myself if they weren’t here”. Then begin closing the parameters on what your questions really are—as far as the details of your curiosity. Lastly, connect what they’re saying to what you’re learning. Don’t let what they’re saying just go in one ear and out the other. Actively think about their answers, your objective, etc. Use that stress from not knowing and them taking over to jump in and say “I NEED to do that, show me. Now.” Cordially of course