Does animal (from the muppets) live in my washing machine?

My Indesit wil153 has just run out of warranty and now developed a fault, like every other appliance i have ever purchased.
On full spin there is a loud banging coming from the drum, this started suddenly, it was fine when last used and then started the banging on the next use but only on full spin.
I have removed the belt to check the main bearing which appears to be fine, the concrete is firmly attached and not damaged, the springs and shocks are attached and appear to be in working condition. I have shaken the drum and spun it by hand and cannot hear anything moving around between the inner and outer drums, any ideas ?