I know it's a bit late, but I had the same problem. I just tightened all the bolts holding the 2 piece tub together, and voila, no more problem.
Now tho, the spring suspension has warn thru the mounting tabs causing the tub to fall on the motor, damaging wiring, blowing a fuse and who knows what else. Hopefully it's still fixable.
I hate this washer, June 2006