Loctite 221 or 222 are two suggestions. I use 222. A very small quantity is needed. This product dispenses easily and you can get way too much. Put a small drop on wax paper. Use a toothpick to apply to female threads in the buckle. You can put some on the male threads of the pin, but it can get transferred to the inside of the strap if care is not taken. Tighten and let it cure for 24 hours. Let us know your outcome. Best wishes, John.