do you need to build the tripple up/out a bit to stop it turning as far ?
with gluing something to the tripples, yes and no,
it will but each time the stopper hits on the tripples it'll weaken any glue that's joined item
what about drilling and tapping a hole where the tripples touch the stopper, and loctiting a H/T bolt into the threads?
use something like a High tensile M8 10.9 bolt with a 1mm thread,
or a Button head bolt might be better, 12.9 high tensile