Incomplete instrument.

(b) Subject to subsection (c), if an incomplete instrument is an instrument under section 42a-3-104 , it may be enforced according to its terms if it is not completed, or according to its terms as augmented by completion. If an incomplete instrument is not an instrument under section 42a-3-104 , but, after completion, the requirements of section 42a-3-104 are met, the instrument may be enforced according to its terms as augmented by completion. (c) If words or numbers are added to an incomplete instrument without authority of the signer, there is an alteration of the incomplete instrument under section 42a-3-407 . (d) The burden of establishing that words or numbers were added to an incomplete instrument without authority of the signer is on the person asserting the lack of authority. Cited. 156 C. 243. A promissory note remains a simple contract and is enforceable as such even though lacking an element essential for negotiability. 181 C. 207. Cited. 203 C. 394; 233 C. 304; 242 C. 17. Where note, when completed, was ratified by two payments thereon by defendants, they could not raise defense of unauthorized completion by party to whom they negotiated the signed note. 4 Conn. Cir. Ct. 620. Defendant endorser who consented to insertions and alterations of checks is disqualified from attaching their validity and his liability thereon. 5 Conn. Cir. Ct. 405.