That looks to me like the potentiometer connected to the knob you are adjusting is not working well. Similarly to the old rotary dimmer switches, or the triggers in your slot-car track controllers, or the volume knob on your old Realistic stereo that crackled when you adjusted it, potentiometers are just little variable resistors. If that knob on your controller was connected to your stereo, it would be crackling when you turne the volume up or down.
Regardless, pitch it. Get a Prodigy and be done with it.
