The DE drive-end bearing takes the greater load. If you hand spin the pulley and it does not almost instantly stop it is running out of lube. These bearings require special urea based grease, green in color. The rear bearing is not as picky. The 6303 bearing is a good size for the job. Replacing it is no more difficult than re-lubing it. I would definetly NOT try to keep going without refreshing those bearings. A goosy loosey front bearing causes stress on the small rear bearing which causes it to self-destruct. The rotor grinds into the stator making sparks. Iron shards fall upon exposed vulnerable electrical terminals and then the serpentine drive belt breaks when the rotor locks up. Skull & Crossbones.