(a) If without fault of the lessee, the lessor, and the supplier, the agreed berthing, loading, or unloading facilities fail or the agreed type of carrier becomes unavailable or the agreed manner of delivery otherwise becomes commercially impracticable, but a commercially reasonable substitute is available, the substitute performance must be tendered and accepted.
(b) If the agreed means or manner of payment fails because of domestic or foreign governmental regulation
(1) the lessor may withhold or stop delivery or cause the supplier to withhold or stop delivery unless the lessee provides a means or manner of payment that is commercially a substantial equivalent; and
(2) if delivery has already been taken, payment by the means or in the manner provided by the regulation discharges the lessee's obligation unless the regulation is discriminatory, oppressive, or predatory.