Yeah, my gf’s SP10 started acting up, then not acting at all. I made sure the tailcap was on tight, but even I overlooked the head possibly being loose. Snugged it up tight, worked fine.

One of my i332s also had a finicky tailcap, thought one I just bought a little while ago was borken, DOA. The O-ring was reeeeeeally tight, and yeah, I had to crank it silly to get it to make contact. Perfect after that.

Always check the tailcaps and heads, and the retaining rings on the switch and driver. Make sure they’re all cranked stoopit-tight before going any further.