Spin cycle 4 minutes very smooth, then very noisy thereafter.
Bearings are sound.
No obvious loose parts.
Could this be a loose object between the drum casing and drum?

Steve Rice, August 2012

If it is a sharp metalic sound could be something in drum, to remove take the element out and fish object out through hole, be carefull when you refit element that the front of the element locates under its bracket in the drum. If the noise is a general vibration of the machine adjust the feet whilst on spin to get optimum balance. If noise is like marbles in a jam jar will be coin in drain pump. Cheers

Kenjo, August 2012