To help sort it out, start, idle, put in "D", hold it back with the brakes and give it a little power, brakes still on, idle, put in "R", give it a little power.
If the pads are sloppy in the holders this will move them back and forth and they should make the noise.
If the pads are sloppy in the holders this will move them back and forth and they should make the noise.