Find audible noise parts

Making a stethoscope jig

Sharpen the tip of the coffee stir stick and attach it to the paper cup.

Find the loudest point.

Find the place where the sound is loudest. The place in the photo was the loudest.

Identify the parts that are making noise.

When the yellow capacitor was floated from the board, the sound stopped.
As shown in the photo, float any suspect components, such as the transformer.

When you place the tip of the listening jig on the yellow capacitor
that is floated off the board, you will clearly hear audible noise.