There is an email group for Pre 1980 Viking Husqvarnas here
https://groups.io/g/vikingsewingmachinespre1980 It is moderated by an ex US dealer (also moderates the Vintage Singer group there). The rules about messages are very strict - you have to cut all irrelevant stuff from previous messages in the thread and be very 'on topic' - and you get told off if you transgress. I can understand that he is busy trying to help a lot of people but I find it a bit off putting so I tend to only read the messages. If you don't fancy signing up yourself I could search for posts on your problem if you tell me exactly which model you have.
I'm sure that the machine is worth the effort. I would have loved to get a vintage Viking but have to admit to having too many machines, especially now that I cannot get up the stairs to my hidey hole in the box room.
I have always found World of Sewing at Tunbridge Wells to be helpful with questions about feet etc for my vintage Swiss Elnas. Perhaps it would be worth giving them a call if you are not too far away? Sadly they have closed their Croydon shop, and moved their Bromley branch way out of town, but they helped me over the 'phone.