Please over analyze this and have fun with it!
What is this "Light-bulb" that you speak of. Here at the Mechanicum we have servitors do the basic tech work such as lighting
Well first they have to set up the Forge World to start light bulb production.....
It takes roughly 2 magos assisted by a legion of skitarii in order to reclaim the light bulbs from Cadia as that was unfortunately the only light bulb producer other then Macragge but Macragge's light bulbs were cheap and burnt out quick so in order to obtain max efficiency the magos has to fight through hordes of traitors in order to reclaim the light bulbs of cadia
Dont think they have light-bulbs in 40k universe. To old tech.
They're too busy praying to this mysterious ancient tech and waving incense around to even contemplate trying to find out what it actually does!
I think they would struggle to back engineer it never mind its functionality
4, one to screw it in, one to place the oil on the fitting, one for the ritual Awakening, and 1 to summon forth the blessed energies