"belts:
Cracks, glazing on
"belts:
Cracks, glazing on the faces of the V, strings hanging, chunks missing - the normal stuff. the first few I changed were due to the fact that they wouldn't 'tighten up' anymore. Found it was due to the surface rust on the pulleys eroding away the face s of the V. Essentially, through many hours of use, the pulleys were sanding the belts, they got thinner, and 'dropped' deeper into the pulleys.
On the impellers - every two years or when any physical damage is visible, whichever comes first. Also check the wear plate and cam for excessive wear or grooving."