glad you joined the fun.
Since there is no standard for router mounting plates, and none for inserts, you are unlikely to find an insert that fits precisely. However, you might want to go to a woodworking store and check to see if there is something that is similar, or even a match. If you can find something close enough, it may that you can sand it down to fit. The other question I have is about how the insert is held in place. Older inserts are held in place with three tiny (easily lost) screws. If the thickness is right, they will be easy to drill. Or, you might find some material of the right thickness you can trim to the right diameter, drill holes, as Roxanne suggested.
Another option is to purchase a different plate, preferably with twist lock (bayonet) inserts, then buy extra inserts, some brands have sets of inserts pre-drilled. It is usually pretty easy to mark out and route a different sized opening for the new plate. Kreg makes some leveling screws in pix you could add if the existing ones must be removed.
Once you get a new plate, you can surround it with boards, which clamped down, will serve as guides for a bearing bit, see pix with blue plate. Add a playing card between the plate and boards to allow slight wiggle room for lifting the plate in and out for easier bit changes. The pix of the red and aluminum plate is the Woodpecker, premium priced, showing a number of interchangable insert plates. They even make a kit with all sizes you might ever need of inserts. And it's twist lock. There are many other very good brands with the twist lock that are about half the price of the Woodpecker plate. The picture of the leveling screw attachment is a Kreg product.
I think the new plate is probably your best bet at this point. No more hassles. The table itself is rather nice, and if you can keep using it with a new plate, I think you'll like it.
I found this number for Freud, 800-472-7307, but the guy who posted it was disappointed.
