I found out the hard way. I got ready to go to work last night and I grabbed my trusty Mag light [2 D model] I turned it on to check out the light and noticed the bulb was very weak OK I will just change the batteries right? Nope I can't get the end cap off to pull out the old batteries even with 2 people and a set of channel lock plyers it is still stuck.
REMEMBER every so often rub some vasoline on the threads so it will open when you really need to
REMEMBER every so often rub some vasoline on the threads so it will open when you really need to