Mag does keep the serial numbers. They can tell you the year and month it was made. The flat tailcaps were used until around 1990. The new style serial numbers all start with a 'C' or a 'D'. The old style serial numbers start with a numeric digit. Maglite Illustrated Parts Breakdown / Parts Lists I hope this helps. Please post any Maglite questions you have and I'll try to answer them!
Maglite Serial Number Breakdown Number
Maglite Serial Number Breakdown Diagram
This is a graphic I did of the Switch Sub Assembly after it has been removed from inside the flashlight's barrel. See the next steps for its removal. I made a graphic rather than a photo because I was very uncertain about how this project would turn out. I am recreating vital steps with graphics.
You can see the fins I broke off. Although two are shown, there are actually four. The Switch Sub Assembly is made of black plastic. I left most of it in the neutral tones rendered in Google Sketch Up for clarity. It is possible to order the switch or the Switch Sub Assembly at this web site. Be aware you will need a couple of special tools, too. When you are finished, the total cost will be almost as much as a new flashlight. I wanted a solution that is more durable, or that I can replace myself without ordering parts from Maglite.
The bulb socket is spring loaded and can move up and down. Part of the reflector rides on the brass follower. As the head of the flashlight is turned, the angle at which the reflector is cut allows the bulb socket to move so the beam of light can be focused from wide angle to a narrow spot.
You will need to remove the Switch Sub Assembly from the Maglite, but more about that later.
Notice the contact for the battery tip that runs through the bottom of the Switch Sub Assembly. There is a corresponding contact point directly across the opening for the switch, which is below the spring under the bulb socket. The switch bridges between these two electrical contact points.