if the switch mechanism is the same as the aa, here is what you do.
1:un-screw the head, remove the bulb
2:prize the black bit that says "do not remove" off the body, a thin knife blade is good.
3:unscrew the end to remove the batteries. this is the bit to be careful, as the switch assembley will fall out with the batteries. catch all the parts, there should be a black circular piece of plastic, with two tiny pieces of copper, one connects to the +ve end of the batteries, the other contacts the rim of the torch at the front, to complete the circuit.
4:wash the torch body in the sink
5:clean up the battery contacts with a little emery paper
6: dry the body out, put the inner part of the switch back togheter
7: ease the inner switch part into the body of the torch and then use the batteries to push it up to the front of the torch, screw the end cap in.
8:replace the outer switch part, put the bulb in to make sure it lights up.
9:undo the battery compartment, grease the threads, do the same with the head of the torch.
10: put in new bulb and batteries.
11: have a pint
12:nearly blind yourself with your bright, finely working torch!!
hope that this helps
steve
ps tried it on my AA, it worked a treat, i cleaned out the threads on the battery compartment as well with a wooden toothpick and a little oil.
sc