I can’t think of much right off hand. I have a similar problem with my Caldera filter if I buy an aftermarket filter the hole in it is just a smidgen big, around 1/32” and it is enough the filter will float up. I made a spacer and attached it to the bottom of the basket and it holds the filter down.
Maybe a little weight in the basket would work for you. Find a rock about the size of a softball and see if it will do the trick.