NoNotAgain
Flashlight Enthusiast
FWIW I myself have had issues with a Fenix TK41 (containing 8 Eneloops) tailcap being hard to remove after long term storage, most likely due to gas buildup in the light.
I've been using the TK41 since first released by Fenix. Both the XM-L and XM-L2 versions. They've been fed Eneloops from day one. The only time the Eneloops have been removed is for charging twice a year.
I've never had issue with removal of the tail cap or head. Been using dielectric grease on O-rings and threads. Never got a wig of anything when opening the light, unlike using CR-123 lithium primary batteries.
I wish Fenix had never discontinued this light as it's the perfect light for leaving in a vehicle year round.