I'm working on a fuel sender problem with my MV. From all the reading I've done across different brands, these things happen: senders die. Many manage repairs, but the rabbit hole can be deep for some. Personally, when I rehabilitated my '75s, I just replaced the sender. I kept the original for repair, but of course, life moves on. If I were you I'd just call it a day and get a new one, as I'll be doing the same for my MV after checking all connectors and wires., including main grounds.