Document notarized but no seal

The document giving me the car was notarized but there is no seal. I am in Connecticut and can’t get the car registered. The title is in my name ( and ) his name. He will not cooperate and his attorney has vanished. What are my options?

If he will not cooperate in helping you re-title the car pursuant to the terms of the agreement, your recourse is to sue him for breach of contract and ask the court to order him to comply with the terms.