That sound often comes from two parts not meeting cleanly rather than too much fruit. My guess is the blade unit is not seated right or the drive pieces are chewing past each other and which makes a harsh grind even with water. Unplug it first. Take the jar apart and check for a thin gasket around the blade base. It should sit flat and continuous. If it fell out or is twisted, the blades can rub and sound awful. When you screw the bottom ring back on, go hand tight and then a tiny bit more. Too loose or cranked down too hard can both make contact noises.
With the jar empty, turn the blade hub by hand using a towel. It should feel smooth with no gritty spots and no side to side wobble. Any scratchy feel points to a bad bearing in the blade unit and that is not fixable at home on a new one. Set the jar on the base and make sure it drops straight down and locks without rocking. If the little drive nub on the base looks off center or chewed, that is the grind you hear. Do a quick test with a cup of water on the lowest setting and keep the run short. If the sound is still harsh, stop. That means a coupling or bearing issue and you should use the return or warranty while it is fresh. Easy fix if it is the gasket.
