Jetbeam Jet III M problems

So my long time Jet Beam has started acting up.
It no longer goes into high mode. Ive disassembled it and cleaned everything. only thing I can find is the tail cap has a brass ring that is broke in the middle. Not sure if its supposed to be like that or if its supposed to be split like a lock ring but I cant for the life of me get it to engage the high mode. Id be happy if I could just get it to go to high and stay there.

Any thoughts?

Try to repair or change a switch.

Im not sure what's wrong with it. Tightening the head doesn't enter high mode. I dont think thats a function of the switch.

That light acts very goofy when its dirty. You said you cleaned it but I would go over it again. All points of contact. I tend to use a brass wire wheel for the threads. I also clean up the ends of my batteries. If possible avoid jetbeams warranty. Used it once. Never again.
Like you said. High mode engages by tightening the head completely so that outer ring contacts the battery holding portion of the light. (im new. I dont know all the fancy terms.) Have you cleaned that ring well? New battery would be worth a shot also.

Pictures? of the split ring

What do you want pictures of? the split ring or ???