here's a tool for the likes of SC850
Pulley Alignment Tool
This tool quickly identifies the two most common types of pulley misalignment – offset and angular – that cause premature failure of a serpentine belt and produce unwanted noise. By simply positioning the tool within the grooves of a pulley and aiming its bright laser beam at an opposite pulley, a single technician, within minutes, can easily measure alignment to less than 1/2 degree on the entire drive system.
The battery-operated tool is compatible with all serpentine belt drives. The lightweight and easy-to-use patented tool includes special laser enhancement eyeglasses for easier viewing in all light conditions, a high-impact resistant plastic case and a user’s manual.
Recommended Retail Price is $199.00
www.gates.com/tools