Screws are held in place by STRETCH of the metal. Repeated applications of hogh temperature tends to cause that stretch to be lost, allowing the screw to back out. Relace the screws, they are cheap and it is good insurance against weakened, "stretchy" screws.
If Loctite was up to the job, the military would surely have specified it's use! They use TONS of the stuff where it is right for the job. Torque is VERY important for adequate "stretch". Use some Blue, if you wish, then STAKE as specified. Do not stake in the same place, move to a new spot. I use a centerpunch. Lay the carrier on a heavy steel object. A sledge hammer or other very heavy tool will do, the ANVIL of your vise (never the jaws) or a thin rag on concrete as a last resort. Using a substantial hammer, deform the key into the head of the bolt. Do not be gentle, whack it! I try to make it very obvious that the key metal is moved into the screw head, maybe even slightly deforming the head. Done properly, the "stake" will keep that screw from moving for the life of the key.
BTW, Loctite works best when applied to CLEAN surfaces only. Wash the carrier, key and NEW screws in a fast evaporating Brake Cleaner. (Primer "N" is best, if you have it.) Allow to dry completely before applying the Loctite. Tighten and stake the screws at once, before the stuff hardens. Once disturbed, after hardening, it is done for. Heat destroys the bond too so application of same helps remove old screws. That sensitivity to heat is why Loctite is not a good solution to this problem. Loctite is really just an anerobic curing plastic.