The noise is loud, but mostly looks to be operating as intended. The reason you don't hear it in test is because test only briefly fires coils. Diverter coils need to stay turned on longer, which doesn't happen in test. Usually dual wind coils are used in these cases (high power and hold), but I don't think STTNG uses them for diverters. Too many coils, not enough transistors.
I would start by inspecting the diverter coils and hardware (bracket, stop, plunger, link, etc). Changing the coil sleeves is a cheap and easy thing to try. If any plunger or stop is mushroomed, get new if available or fix them with a file if not.
San Diego, CA
