Belt dressing won't help, ever. It is too sticky at first then drys to a hard slick finish.

The source of flat belt noise is the back of belt is sliding front to back across the flat pulleys making the chirp. ( not a slipping in rotation problem )

First, clean all of the dressing off the pulleys, this will be difficult and time consuming.

Sand the flat pulleys in a cross hatch pattern with 80 grit paper leaving them slightly rough. Paint isn't an issue as bare steel can be noisy as well.

Lightly sand the label on the belt, just take off the slick shiny surface, no need to remove the numbers. This is the source of a cyclic chirp.

The goal is for the pulley to grip the belt rather than letting is slide front to back across the surface.

As stated above, never use belt dressing.

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Jim

Honestly. this might have been my only initial problem..