Crossovers are the dictating factor in how a speaker sounds. Each capacitor and coil on the crossover board influences the frequency and tone of the signal that those components are responsible for. If a woofer or tweeter stops playing and the driver is found to be operational, it is probably necessary to replace a component on the crossover.
Heat up the soldering iron to its normal operating temperature. This is usually indicated by an amber light turning off after the unit heats up.
Turn the crossover face down, with the solder joint balls facing you. Heat up the solder joint on the bad component until it begins to melt.
Hold the soldering iron against the joint as it melts. Simultaneously hold the solder sucker over the melted solder, and move the plunger back to extract the melted metal.
Clean up any excess melted solder with the wick. This will soak up any excess, leaving a clean board.
Gently pull the old or damaged crossover component free of the board.
Turn the crossover board, with the components facing up. Bend the wires on the new component. Slide the wires through the holes previously occupied by the removed piece.
Tape the component in place using a length of painter's tape.
Place the solder against the tips of the wires belonging to the new crossover component, sticking slightly through the bottom of the crossover's board. Set the hot iron against the wire and solder, allowing a small bead to flow over the board and the wire tips.
Allow the solder to cool. Remove the painter's tape from the component.
Bad capacitors generally have a burnt, brownish appearance. Additionally, you may see the cap of the crossover unusually bulging from the top, or a brown/black sticky flow from underneath it.