you can make your own insert out of plywood, about same thickness as you old one. Cut and fit, shim to get level if needed, and install. Slide the fence over the side, start the saw and crank the blade up, giving you a zero clearance slot. Go a little higher, and then drop the blade to where needed. Have had several of different slot sizes for years, and they work great. USE A PUSH STICK!!! Make some (a lot) out of 1/8 or 1/4 masonite or plywood, they are a consumable. Keep your fingers away from the blade!!