Considering Logan QTC with momentary switch...if the QTC pill dies and no amount of screwing the head in and out can turn the light on, the momentary switch is also kaput?
(And if so how to replace these consumables. The QTC pills that is.)
Any failure of the QTC would leave the light with just two modes: OFF and HIGH, so the momentary should still work fine. The QTC pill and the QTC material itself are very easily replaced.