You can't sue the realtor: the realtor is not obligated to do research to determine if there are any issues but can rely on what they are told by the seller.In theory, IF the seller knew of the issue and failed to disclose it, he could be liable--but only if he knew: there is no liability if the seller was innocent of knowledge of the problem. However, in your state (MN), the "statute of limitations," or time within which to sue, for a misrepresentation or failure to make a required disclosure (fraud) is only 6 years, so if you bought the property 8 years ago, it is too late to hold the seller liable even if he did know and intentionally hide this.Similarly, while the title company could theoretically be liable for missing this, it is too late to hold them liable: the statutes of limitation for all the possible grounds to sue them (fraud; breach of contract; professional negligence) are all less than 8 years.Your only recourse may be if you have title insurance that is in effect; if you do, you have whatever rights and recourse it gives you.