Prise off the small oblong rubber block near the top (not sure if this is essential but I did),then screw on an old brush head.Put brush head in vice then tug the main body till the outer case sides off-it is tight and seems to be glued with a powdery type cement. Yo will see the batt. which looks standard C ( I think).Did not take out batt so cant comment on that bit but it does not look too tricky.I stripped mine cos the rubber switch cover had split and would have let in water-so sealed it inside and out with silicone also used for sealing on reassembly.Nothing to lose-option is to bin it,hope this helps
Al
December 2009