Washing Machine jumps when done with wash cycle?

Top loading Whirlpool washer makes a loud bang and jumps, once (torquing to the right) when it stops at the end of the wash cycle. The machine will turn several inches out of position. It's 5 years old, and started this a year or so ago. Seems to be getting worse. Everything else is fine, this has nothing to do with uneven loads or the final spin cycle. After the one loud bang and jump, the machine proceeds with the rinse and spin cycles just fine. This is not continuous vibration or noise, just one single loud bang and jump at the end of wash. Any ideas? Thanks.

Tom
January 2011