Bosch WAA28167 GB/32 washing machine

During normal use, at the spin cycle a bang was heard and a smell came from machine but the drum kept turning. The machine was switched off from the main control switch, the drum slowed and stopped. After delay the drum was opened and white “smoke” appeared to come from inside the drum (surprisingly). The clothes were removed and after a few minutes (with windows open) the smoke cleared. The machine was left until the following day before checking. No damage could be seen with the top & back removed, the pump & filter filter was checked before testing the machine on “Rinse” mode with no load. The machine ran ok, water emptied ok but the drum could be seen to be rotating off-centre i.e was not balanced correctly. On the spin cycle this produced a wobble which got worse as the speed increased. I suspect the drum bearings are gone. Are the bearings sealed or replaceable? Is the machine repairable and what might the cost be DIY or by service agent? I would appreciate advice on this.