Belt Drive Washer: Drum will not spin

Hi, I hope someone can help on this one. Got an old Whirlpool belt driven washing machine. I checked the belt and it's on good condition. The belt will spin the shaft without catching in either direction. The drum inside doesn't move when doing this. The water will fill and drain going through the cycles and the agitator works. The motor sounds like it's working while trying to spin, if I have my timing and cycles down right. I think the big indicator of the problem may be that the drum inside is locked in place. I would use the word seized up. It doesn't seem to want to move either direction nor will it tilt or give to one side or the other as I normally have seen all my life. Any assistance on where to start would be greatly appreciated! Best Regards, Ben