. I'm thinking of getting a tad customs and 140 lumens bi pins for my E2d.
That's the wrong lamp for 2 cells (unless you are runnng 16650 secondary cells, or are bored for 18650). The 140 lumen A3718 is for one Li-ion secondary cell only. You are welcome to try it with 2 cells, but I promise you that you'll instantly flash the lamp at every attempt.
Depending on whether you are running 2 primary or 2 secondary cells,
the proper lamps for E2d is either the
120 lumen
A4812 (primary only) or the
200 lumen
A7212 (secondary 3.7V cells only, IMR recommended) or the
150 lumen
A6010 (secondary 3.2V LifePO4 cells only).
Look at Tad's lamp chart. Keep looking at it. Keep looking. Eventually it makes sense, I promise. Pay attention to the amps and voltage specs of the lamps, and identify them by their name, A3712, A3718, etc, not by the lumens stated.
It is not often the lamp dislodges from the socket. Happens sometimes if you drop the light on its head over and over. Before you attempt solve "the problem" with glue... better make sure it is actually a problem for you. I have been running Tad's lamps for a couple years of heavy use, and only very rarely do I need to tap the light on its tail to force the bipin to settle further in the socket.
If anyone has had a Tad's lamp completely dislodge from the socket, I'd like to hear it. The worst I have seen is the light will go intermittent when using certain angles. Tapping the tail on a hard surface corrects (rather than pulling the socket and pushing the lamp back in).
I like to run dimmer lights, so I often use the A6010 with a single cell, but it is dimmer and yellow because I underdrive it. Best performance is when voltages match.