I’m having trouble getting my front sprocket off. I have a breaker bar and the correct socket. But when I try to get the sprocket off, it moves. The chain is still on and I used the brake to stop the back wheel. I also put a piece of wood to enforce the stopping of the wheel but still nothing. I don’t have any pneumatic tools. I don’t want to mess anything up since it’s a major part of operation and probably an expensive fix if something breaks. Any recommendations??