That is the way of adjustable stems. Even good, new, strong ones. Problem is that there is a tremendous amount of torque on that hinge. No bolt could secure it for long.
I am pretty sure that Locktite will not solve it for more than a day or so. Products like that have virtually no shear strength.
jim
__________________
Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
--------------------------
SB forever