Which replaces the bulb in a normal fashion and no dismantling of the M@g body is required.
The other is a ceramic slug which is replaced by following the steps below.
1. Taking the head off is correct. 2. Than take off the tail cap. 3. take out the Batteries. 4. Remove the rubber switch cover (I use pliers at the edge but gently pull it out). 5. Place a hex wrench (I think a number two) down the centre of the swich and loosen the screw. 6. Once the screw is loose, press in the switch and hold it down while sliding the switch assembly to the rear of the body. 7. Now you are almost done. 8. Remove the screw from the side of the slug and remove the slug. 9. Be careful not to loose all the springs inside. 10. Now replace the slug with the new one and be careful while putting the screw in the side of the new slug as you can cross thread them easily. 11. Now just reassemble you beefed up light. 12. You need to push the switch back down to get it back into position.