(a) Waiver of disposition notification. A debtor or secondary obligor may waive the right to notification of disposition of collateral under section 9-611 only by an agreement to that effect entered into and authenticated after default.
(b) Waiver of mandatory disposition. A debtor may waive the right to require disposition of collateral under section 9-620(e) only by an agreement to that effect entered into and authenticated after default.
(c) Waiver of redemption right. Except in a consumer-goods transaction, a debtor or secondary obligor may waive the right to redeem collateral under section 9-623 only by an agreement to that effect entered into and authenticated after default.