You can put the stator support splines in the converter to engage it, then rotate it back & forth, try to make a complete revolution & see if it jumps/binds/hangs up in the free-wheel direction. Anything other than smooth & free is not OK. You can then check the turbine the same way with the input shaft, it should be free & smooth both directions,.....often if the sprag fails hard enough, it can spit damaged rollers out, they will be floating & getting knocked around in between the housing/impeller, turbine, & stator blades.