There are several signs a pulley is no longer functioning properly. First, check for free rock. There should be no movement or play from side to side. Next, look for misalignment. It will cause a belt chirp noise and is often the result of worn bearings. Spin the pulley with the belt removed, if it spins more than one revolution, the bearing grease is depleted…

A belt tensioner should be replaced if any of the following issues are noted: You hear noise or feel resistance as that could be a sign of potential bearing failure. The belt is not tracking correctly as that could mean a loss of tension. There is sticking or notchy movement. With the belt removed, use a tool to move the tensioner through its entire range…