New from "Decware" Steve Deckert is known for quality parts. This may be another good option for this rectifier. I ordered one to test will report back in due course......cheers
https://www.decwareproducts.com//product-page/russian-5u4?utm_campaign=bbe4740e-c455-4237-a085-77cdac1c3aea&utm_source=so&utm_medium=mail&cid=27ad52a9-8dd7-4ca0-9cde-721af8c9e8b4
https://www.decwareproducts.com//product-page/russian-5u4?utm_campaign=bbe4740e-c455-4237-a085-77cdac1c3aea&utm_source=so&utm_medium=mail&cid=27ad52a9-8dd7-4ca0-9cde-721af8c9e8b4