A resonator is a type of acoustic guitar distinct from typical acoustic guitars because it has a steel-fronted resonator cone that gives it a characteristically bright tone. Resonator guitars have a similar anatomy to normal acoustic guitars and suffer from many of the same snags, such as rattling. There are various reasons why your resonator might rattle; some issues are simple to fix while others are somewhat more complex. When troubleshooting a buzzing resonator, always investigate the most simple-to-fix problem first.
Tighten up all exterior screws. A common cause of buzzing is loose fittings. The screws rattle as the strings vibrate. Use a small Phillips screwdriver to tighten up each screw of the six tuning machines and both strap buttons.
Test the guitar by playing some loud, open chords. If the buzzing has diminished, tighten the screws a little more. If tightening the screws has made no difference, continue troubleshooting.
Play the first three frets of each string, starting with your top E. If the string action is too low, the strings will rattle and buzz against the frets. This is particularly pronounced on the frets nearest to the nut. If there is residual fret buzz, the string action is too low. Correct this by raising the height of the bridge to move the strings away from the fretboard. Fret buzz is the most common source of buzz on guitars.
Loosen all strings and remove the ball ends from the bridge. Pull the strings out and discard. Unscrew the resonator cone cover plate with a Phillips screwdriver. The screws are fastened to the front of the guitar. This exposes the "spider assembly" upon which the wooden saddle is mounted.
Pry the saddle out of the spider assembly with a flathead screwdriver. Slot in the taller replacement saddle and gently tap it down into the spider assembly groove using a ball-peen hammer. Unfortunately, acoustic and resonator guitars have fixed-height saddles, so if your saddle becomes worn or sinks, you need to replace it.
Examine the resonator cone. While the cover is off, look inside the guitar. Cracked or loosefitting resonator cones will create a distinctive metallic buzzing sound. The resonator cone fits in a sound well and is typically not glued or screwed in. If you spot any damage, remove the resonator cone through the front of the guitar. If the resonator cone is in good order, replace the resonator cone cover and fit a new set of strings.
Slot a replacement resonator cone through the open front of the guitar. Position it so that the edge of the cone lies flat against the rim of the sound well to avoid rattling.
Replace the resonator cone cover, ensuring that the screws are correctly tensioned. Put on a new set of strings.
Slot a piece of felt in between the tailpiece and the body of the guitar, which will absorb any residual rattling caused by two touching metallic parts.