Andrew (Sandy) is correct that there is no state agency that has responsibility for enforcement of statutory road associations. He is also correct that a flawed process could keep a road association from being able to collect on notices of claim; however, that would necessitate the matter ending up in court.
I don't know if the Office of the Attorney General would do anything for you. I do know that they deal with consumer complaints regarding businesses, charities, and housing, but I'm not sure if a road association fits any of those categories.
Another possibility might be to seek the services of a professional Mediator. You could try the Maine Association of Mediators, or Family and Community Mediation (FCM).