Generate some PM.

Pulleys

The V-belt passes over the pulleys at high speed. That builds up a lot of friction between the belt and the pulley grooves. So take a close look at the sides of the grooves on each pulley. If the grooves are cupped, the pulley is no good. Replace it.

Next, eyeball the pulleys where they come in contact with the V-belt. If the belt bottoms out on a pulley, the grooves are too worn and the pulley should be replaced,

Check to make sure the pulleys are straight. A belt running on crooked pulleys will wear out much faster than on aligned pulleys.

Hold one end of across the face of the on the harmonic balancer and the other end across the face of the pulley on the bearing unit. Pull the string tight. If there are no bends in the string and no gaps between the string and the pulley faces, the pulleys are in alignment.

V-belt

When changing a V-belt, don't stretch or roll it onto the pulley. There's a good chance the V-belt will suffer damage and early failure.

Always release tension first, then slip the V-belt in place.

Once the V-belt is in place, don't rely on a "calibrated thumb" to adjust the tension. Always use a scale to measure deflection. Then, after the vehicle has been operating a few hours, check and adjust the tension again if needed.