What type of riding do you do? That 15t front is tall, and that is not helping you out of the hole. You should be able to grind/cut that weld off. You can't expect that sprocket to hold up to the life of the bike, anyway. Go back to a 14t, or a 13t if you ride in tight trails. This will make it much more fun to ride. If not, get a huge rear sprocket.