Help with Foursevens Quark Mini ML!

Hello everyone,

I just sold a titanium Foursevens Quark Mini ML to a lovely young man, and the light was working perfectly when it was in my hands. Unfortunately, it just started giving him some trouble, so I wanted to see if anyone here might be able to help us trouble-shoot! The light has been finicky and has alternated between working appropriately and getting stuck “on,” where he unscrews and unscrews the head to the point where you wouldn’t think the battery is contacting the head anymore, yet lo and behold there’s still a glow coming out of the light (I saw this on video myself). He tried cleaning the battery contacts and this helped for a bit, but then the light will switch over to being stuck on “low” and will not cycle through the other modes. He owns the same model and is familiar with how to cycle through modes.

Does anyone have any ideas for what might be going on or recommendations for us to try?

Thank you for your input!