Solution to the spring, pop off the bottom, stretch the spring on the loose cell, even if it sits a tiny bit higher it will compress down
(I know stretching the spring slightly on my vaping rigs solves alot of the "loose battery" problems
Seems everyone and their mother in law is pumping out SRK's with different drivers and whatnot, if you get a good one cool, if not, there are tweaks...we are all waiting on texaspyro mega sweet SRK OSHPark driver though, until then many are making due adding on the ATTiny13A microcontroller's on top of some of the weaker current drivers that are out and really making them incredibly useful and much more powerful
like this https://budgetlightforum.com/t/-/24491