I have an extra sump-side downpipe/valve. If you need an extra, might be some inexpensive insurance to have on hand. $50 pickup in Tualatin. Cash or PayPal (you pay any fees).
This pipe is slightly used, but not much
Red Sea Reefer 250/350/450, XL 425/525 & Max-E Aquarium Replacement Sump Valved Downpipe (Red Sea Part # 42217) (marineandreef.com)