That media basket is pricey so I would also avoid it. First I would verify that the filter actually does work properly since you haven't used it in years. I'd set it up without any media and do a test run if you can either using a 5G bucket of water or the tank if you already have water in it. Definitely check the pump head o-ring to be sure it is in good shape as well as the impeller and shaft.
If everything does work well, you can use one or two pieces of egg crate (drop ceiling light grid) cut to shape to use as the bottom lattice screen and then also use some Poly-fil Traditional Batting cut to wrap around the original coarse blue sponges to fill the gaps or just cut larger and layered between the blue sponges. A final piece of egg crate can be used just below the original top lattice screen to prevent material getting past it.
If everything does work well, you can use one or two pieces of egg crate (drop ceiling light grid) cut to shape to use as the bottom lattice screen and then also use some Poly-fil Traditional Batting cut to wrap around the original coarse blue sponges to fill the gaps or just cut larger and layered between the blue sponges. A final piece of egg crate can be used just below the original top lattice screen to prevent material getting past it.
