It sounds like your speaker might have a couple of potential issues. Here’s a step-by-step troubleshooting guide to help narrow it down:

Inspect the Driver: Remove the speaker grille (if possible) and visually inspect the driver for any physical damage like tears in the cone or deterioration in the surround. A damaged driver often leads to distortion.

Check Connections: Ensure all connections, including internal wiring, are secure. Loose connections inside the speaker can cause intermittent sound or distortion.

Test Individual Components: If you can, test the driver and tweeter individually using a multimeter to check for impedance consistency. A blown driver or tweeter may cause distortion.

Examine the Crossover: The crossover network might have failing capacitors or resistors. Inspect it for any visible damage, such as burnt components, or consider having it tested/repaired by a professional.

Amplifier Compatibility: Ensure your amplifier or receiver is not underpowering or overpowering the speaker, as mismatched power ratings can cause distortion.

If you’re comfortable with DIY repairs, you can replace faulty components (drivers or capacitors are common culprits). Otherwise, a professional repair service might be worth considering, especially if you value the speaker’s sound quality.