Bosch WVF2000 washer/dryer - inner drum seems loose?

Bosch WVF2000 washer/dryer (about 6-7 years old?). The motor wants to turn drum but stops with a thump, although the drive pulley etc all seem properly adjusted, bearings okay, etc. The inner drum can be rotated by hand from the inside, but it feels like it is lying at the bottom of the outer drum. Is it common for the inner drum axle/shaft to snap? Or come loose? Is the shaft itself replaceable, or only together with the inner drum? What part numbers do I need, please? many thanks!