You will have to take the collar off of the back of the drum, undo all the bolts round the back of the drum, disconnect all the wires (remember where they go tho) you can then remove the back of the drum ( be carefull of the element - I would take it out b4 you remove the back). You may have to use a screwdriver or something to "encourage" the back to come out as it may be gummed up (Probably will be) with scale.
Be carefull of the seal it may be perished with wear, or get damaged during the repair. If you are not happy with the integrity of the seal when you examine it then just replace it with a new one.
Once that is done you can remove the old bearing (you will probably have to use a bearing extracter to do this) replace with new one and just put it all back together. Done
This should take about 2 hours if done properly
Les Robertson, December 2007