When the secured party is not required to "apply or pay over for application noncash proceeds," the proceeds nonetheless remain collateral subject to this Article. See Section 9-608 [Maine cite section 9-1608], Comment 4.

4. Surplus and Deficiency. Subsection (d) [Maine cite subsection (4)] deals with surplus and deficiency. It revises former Section 9-504(2) by imposing an explicit requirement that the secured party "pay" the debtor for any surplus, while retaining the secured party's duty to "account." Inasmuch as the debtor may not be an obligor, subsection (d) [Maine cite subsection (4)] provides that the obligor (not the debtor) is liable for the deficiency. The special rule governing surplus and deficiency when receivables have been sold likewise takes into account the distinction between a debtor and an obligor. Subsection (d) [Maine cite subsection (4)] also addresses the situation in which a consignor has an interest that is subordinate to the security interest being enforced.

5. Collateral Under New Ownership. When the debtor sells collateral subject to a security interest, the original debtor (creator of the security interest) is no longer a debtor inasmuch as it no longer has a property interest in the collateral; the buyer is the debtor. See Section 9-102 [Maine cite section 9- 1102]. As between the debtor (buyer of the collateral) and the original debtor (seller of the collateral), the debtor (buyer) normally would be entitled to the surplus following a disposition. Subsection (d) [Maine cite subsection (4)] therefore requires the secured party to pay the surplus to the debtor (buyer), not to the original debtor (seller) with which it has dealt. But, because this situation typically arises as a result of the debtor's wrongful act, this Article does not expose the secured party to the risk of determining ownership of the collateral. If the secured party does not know about the buyer and accordingly pays the surplus to the original debtor, the exculpatory provisions of this Article exonerate the secured party from liability to the buyer. See Sections 9-605, 9-628(a), (b) [Maine cite section 9-1605 and section 9-1628, subsections (1), (2)]. If a debtor sells collateral free of a security interest, as in a sale to a buyer in ordinary course of business (see Section 9-320(a) [Maine cite section 9-1320, subsection (1)]), the property is no longer collateral and the buyer is not a debtor.