Very frustrating situation, going to blow some steam!

Sounds to me like you may have a lemon on your hands. You also sound like you want to get rid of it, but need someone to justify your reasoning. My question to you is it worth the hassle and stress you are putting yourself through for 4 times a year usage? Sell it and move on to either another chapter in your life or buy a good used trailer. I wouldn't buy new for the little use you have.