Guys: I am flying an LA-2 with a very good YS 61R Long Stroke. After about 3 flights the bolts in the heading come loose or fall out altogether. I have cleaned the threads in the head as thoroughly as I can with denatured alcohol, have dropped a drop of red 271 Loctite in the bolt holes and on the threads and have screwed them in with an L wrench socket head wrench. The engine is on a soft mount. I get about three flights and the bolts always come loose or come out altogether. Anyone have any ideas on what I can try to do?

Thanks, Bill