Which of the following is a common malfunction in railway switches?

Misalignment of switch points is a common malfunction in railway switches because it directly affects the ability of the switch to guide a train from one track to another safely. When the switch points—the movable rails that direct the train—are not properly aligned with the main track, the risk of a derailment increases. This malfunction can occur due to wear and tear, mechanical failures, or environmental factors, and it is crucial for railway operations to maintain proper alignment to ensure the safe and efficient movement of trains.

The other options, while they can impact railway operations, do not specifically pertain to the function of switches. Excessive speed of the train pertains more to operational safety rather than a malfunction of the switch itself. Debris on the track is a general hazard that affects all aspects of rail safety but does not specifically indicate a malfunction of the switch system. Improper signaling relates to communication between trackside signals and trains, which is essential for train control but is separate from the mechanical functioning of a switch.