My enclosed trailer is starting to leak around the seams when it rains. It looks like a previous owner sealed them with something but the sealant is cracking. Does anyone know what this sealant is? Can I apply something right over the top of the old sealant or do I need to try to remove it? What product works well for this? I bought some flexible window and door caulk at lowes yesterday but now I am not sure if it is the best thing to use.