What I always do is take the adapter and turn it upside down. Then, holding it tightly and square, take a big socket and place it in the center and smack it a couple times with a hammer. It will deflect the center back outwards slightly. These adapters distort inward when the fitting is tightened and can be a nuisance for leaks when reused. I've done dozens of these in this manner, on just about every small block I build anymore, and it works great every time. If you're considering getting a new plate anyway, you're not losing anything by trying, right? It's worked well for me!