What potential risk is associated with improperly holding the master controller?

Improperly holding the master controller can lead to overheating and excessive wear in the electrical components of the train's control system. This sustained pressure may cause components such as resistors and relays to experience increased stress, resulting in potential burnout. The electrical system is designed to handle specific loads, and any irregular or prolonged use of the master controller beyond its intended operation can disrupt the flow of current and generate heat, leading ultimately to component failures. Therefore, understanding the importance of proper handling of the master controller is vital to maintaining the integrity of the train's electrical systems and ensuring safe operation.