washing machine tub jerks violently when stop spin?

I jsut replaced the rbber cog between the motor and transmission layed it down to work on it with the side panel off , reeplaced the part stood it back up , and now it jerks the basket violently when it stops spinning...a small bracket came off from somewhere when we stood it back up (aproxx 4 inches long ) but I can seem to see where it came from...it never had this problem before...this is a sears kenmore, aprox6years old...cheap model. thanks for your help,Debbie