Also make sure you clean the loop on the upper mount that the belt runs through at the top -- over time, sludge will build up on the surface of the plastic, and gum up the movement of the belt through the loop. If my old brain serves me, there was a TSB on this once upon a time -- specifically for Corollas and Chevy Geos, but I think it also applied to all Toyotas. The TSB involved both cleaning the upper mount, and sticking some adhesive-backed super-slippery plastic film onto the mount underneath where the belt slides through. Did this on my wife's old '94 Geo, and it worked great. Just cleaning the upper mount is almost as good as having the plastic film in there.