We were in the trailer last weekend when it started pouring rain. Water started dripping into the trailer around both skylights. I went up on the roof after and I can see how the roof sealant is crack...
If the original sealant looks good, and is fastened solid, I would clean up the old sealant in the cracked areas. I have used glass cleaner with ammonia with good results. After cleaner is dry, cover the cracks with self leveling dicor.