My son put brakes, rotors and drums on my car. I keep hearing a tapping noise. on 2007 Ford Taurus

The noise is in the back brakes. It's only when I push on the brakes.

Asked by for the 2007 Ford Taurus
re insp them poss a loose spring or adjuster
Rear drums may haave to be turned.
I've reinspected them, It's in the passenger rear brake. Everything looks good, but still hearing a knocking sound when I hit the brake.