My Eureka 4870 has no suction on the floor or hose setting, white air blows out the front filter. Further, the roller does not move when on the floor setting. The belt is in good condition and I cannot find any blockage in the tubes. The only suction is underneath the bag (weird).
clean out the stuff plugging it. Check holes in tubes.
Its plugged somewhere and if the discharge air is blowing dust and not very hard then whatever filters the air is plugged too.