how can i mend the banging noise coming from the drum?

TURN OFF AND UNPLUG THE MACHINE and remove the lid. Check that the concrete balance blocks are not broken or loose. Check that four suspension arms are connected to the drum and main body.
The large hard plastic drum should be level and straight within the machine.
Have a look down the back where the belt attaches to the drum wheel and see if anything is hindering the wheels smooth movement.
Check if the access plate on the back of the machine which covers the drum wheel and belt is NOT hitting the wheel. If it is striking the cover, take it off, place a thick washer between the main body of the machine and the cover then re-attach using the screws. This will move the plate back, hopefully enough, to allow unhindered movement.
An item, like a coin or nut etc, can sometimes slip down into the void between the steel drum and it's hard plastic outer surround.
If this is the case, and engineer can remove it. If YOU want to try.... Take the machine outside, put it up on blocks for it to be level and you can access the underside. The hard plastic drum has many bolts holding it together, so if you remove as many as you can see underneath, you may be able to pry the surround apart just enough to pour water into the machines main drum and flush the foreign body out.
Maybe worth a try, if you are sure this is the problem, before phoning for an engineer.
Good hunting.

Davy Mac
June 2009