I have a G E washer doing the same thing. It's a G T W 465. A tad over two years old. From what I have found, there seems to a lot of this sort of failure (Hooray GE, make it cheaper). I'll price out a replacement transmission if I can find one but I suspect the Whirlpool company will be getting a new customer. Attention: Appliance Parts Pros. Stock up if you can get them.
Symptoms: Small amber colored oily pool on the floor, oily substance covering the belt and inside the removable housing.