I have no real expertise on this, and gladly defer to others who do. I'm simply going to tell you what I did, which has produced acceptable results for my limited purposes / use.
For the record, I consider the AA MM to be an important, major milestone in the development of the flashlight, I appreciate what it offered, and feel it earned a place in the Smithsonian. Somewhat ironically, I also personally disliked using them for years.
I recently discovered a mint early '90s AA MM I had packed away and forgotten, and for purely nostalgic reasons (not practical personal need) wanted to modify it so it would be at least justifiably and practically usable for me in limited service around home. I wanted to enable it to produce a usable amount of light, while eliminating what I consider to be two absolutely fatal flaws in its design (which caused me to ultimately completely stop using them).
A local company produces / sells some 'upgrade' parts for them, and I decided to give their stuff a try. I installed one of these kits consisting of an LED 'drop-in' module, and a suitable aluminum reflector which is superior, and can better deal with the LED's heat. This produces what I consider a 'usable' amount of light for my particular purposes:
Over 1,200% more light - Full Power Mode (180 lumens) - Dimming Function
littindustries.com
To make it usable for me also required provision of a proper switch, which (IMO) the MM always lacked, and sadly still does to this day. I needed a pushbutton tailcap switch which would match the functionality of the '50s vintage 2xAA 'penlight' I had as a small child, and which helped fuel my interest in flashlights forever. For this, I installed one of these:
Machined from 6061 Billet Aluminum - Allows for one handed operation
littindustries.com
This has met my limited objectives. I now have a MM that is close to what I always wanted it to be, but which it never was before. It now produces a 'usable' amount of light output for many tasks around home. I can now operate the light with one hand quickly and reliably under
all conditions. I no longer have to deal with the beam focus / adjustment "feature", which IMO was never more than marginally worthless on the MM model specifically, but also was a major detriment due to its requiring 'adjustment' just to simply turn the light on / off. I've wrapped the head threads with some Teflon tape to add some resistance to being turned unintentionally, so that's effectively out of the equation now (finally!).
The original PC lens / window remains, and with continuous use may or may not be up to the heat generated by the LED. If I ever use the light enough that this becomes an issue, I'm sure I could replace it with a Borofloat or similar replacement. I don't expect it to be a problem given my limited duration / frequency of use.
So, I spent $38 on a light that probably wasn't worth 10, cannot match most of the other lights I have, and would never be sufficient to replace any of the lights I carry every day. Pure nostalgia. Was it worth it? Dang right, it was for me.
There may be superior parts available which I'm unaware of and which might be better for the purpose, but this accomplished my limited personal 'mission'. Those with actual expertise in modifying lights may well have better suggestions - this is just one approach that worked for me.
EDITED for correction and smoothing some rough edges.
