Why has my Bosch Exxcel 1600 stopped spinning?

This machine has been getting louder and louder recently on it's spin cycle, to the point where we can't hear ourselves speak and it sounds like it's about to take off or explode! The banging sound is quite scary. Today it stopped in the middle of a washing cycle and tripped the power downstairs. When I switched the elec back on the machine carried on with it's cycle but did not spin. The washing came out soaking wet. Any ideas on what's broken and how to fix it?