There is a French tank bag manufacturer called Top Sellerie, which is very similar to Baglux. I have their tank harness and bag for my Fazer. Maybe they could supply the necessary spare parts. Failing that, a company called Alfatex(ebay) that make lengths of sturdy velcro that has a buckle loop on one end, in both plastic or metal. I use these for compressing tents to make them easier to get in the accompanying bags. You might be able to make them work. I did replace the side clups on a baglux a few years ago but can't find the details of where I got them from. Last resort maybe buy the cheapest baglux harness on ebay/gumtree etc and cut off the necessary strap.