[mikejb]

You have to make the connection though: that clacking noise is probably that new system I read about doing something. Then you have to determine whether that system is the cause of the problem, and whether disabling the system will either fix the issue, or possibly make it worse.

[WalterBright]

The clacking sound happens whenever the stabilizer trim is in operation, which is frequently, and has been in 737s for decades.

The pilots would be very familiar with the sound and what it represents. The trim wheel also spins when the trim is running, a large and obvious indication (I posted a link to a photo of it).