Final answer:
A driver should adjust automatic slack adjusters only if the automatic adjustment mechanism fails, typically during installation, maintenance, or troubleshooting of brake issues. It's essential for vehicle safety that a professional checks the adjusters if problems are suspected.
Step-by-step explanation:
A driver should adjust automatic slack adjusters only if the automatic adjustment mechanism is not working properly, as this could affect the brake performance. Automatic slack adjusters are designed to maintain the correct tension in a vehicle's brake system automatically, and therefore, the need for manual adjustments should be rare. Typically, manual adjustment is only necessary when initially installing the automatic slack adjusters, during routine maintenance or when troubleshooting a potential brake system issue. It's crucial that if a driver suspects there is a problem with the adjusters, they are checked by a professional to ensure the vehicle's brake system is functioning safely and effectively.