A system and method for controlling the position of a filler wire and/or a laser head, or other heating head, in a welding system. The distal end of the filler wire is gradually moved, e.g., upward, until electrical continuity with the weld pool is lost; the filler wire is then moved back into contact with the weld pool. The heating head may be stationary relative to the weld pool, or it may move, with the distal end of the filler wire, relative to the weld pool.