A warn belt usually has excessive play or deflection as well as narrowed width and glazing...however with Kawasaki's CVT design, it can also have a glazed under side where it rides on the primary's spindle which may also cause some pulling or squealing. A full inspection should be done. The specs are in the manual. If out of spec or glazing is noted, replace the belt. The factory always sets the deflection on the first one and there is usually enough shims in the secondary to take care of most any needs. However, any parts house like cheapcycleparts.com will have extra shims. Be aware that you will have to either buy, build or borrow a spring compressor to dismantle the secondary. As you may need to pull the primary, there is also a special puller needed as well as a torque wrench for installation. There are some YT vids that can help you.