The only way the front bolt could be off centre is because of keel stub problems. If something was hit it would try to drive the keel's aft end into the hull. The total number of bolts would limit its movement. If it's off centre I would look at the keel stub - is it wood cored as some are? If it's solid glass there is not much chance of the keel moving off centre. I think that replacing the front bolt will not be the solution by itself. You have to find out the cause of the problem to find the right solution.