(a) A debtor or secondary obligor may waive the right to notification of disposition of collateral under Section 9611 only by an agreement to that effect entered into and signed after default.
(b) A debtor may waive the right to require disposition of collateral under subdivision (e) of Section 9620 only by an agreement to that effect entered into and signed after default.
(c) Except in a consumer-goods transaction, a debtor or secondary obligor may waive the right to redeem collateral under Section 9623 only by an agreement to that effect entered into and signed after default.