Well Donna, that's a great question. In most states,Realtors are compelled to disclose;information only 'known' to them. Anotherwords, if the flaw is not an obviouse one, or a condition that should be known to a proffessional Realtor; in thier capacity as an 'expert', then; the Realtor, in most cases is held harmless.
Disclosure and the buyer's acknowledgement of that disclosure, is manditory;as to real estate practice in the U.S.
Generally, what I find to be the case in the after the fact disclosure of a minor flaw,is that the seller, if approached to do so, will generally 'cure' the condition.
I have seen property line, as well as use issues go to court, however, this is rare, and is far less expensive to resorve through resolution.
1. Ask the seller to remedy the flaw.
2. Press for resolve through mitigation.
3. Go after the broker's E&O insurance.
4. Take an asprin or tylinol; and walk it off.
5. Go after the title insurance.
6. Take it to small claims court.
THat's about it. Good luck!