FIG. 1 is a perspective view of the replacement head embodying the new design; FIG. 2 is a right side view of the replacement head, the left side view being a mirror image thereof; FIG. 3 is a front view thereof; FIG. 4 is a rear view thereof; FIG. 5 is a top view thereof; and, FIG. 6 is a bottom view thereof. FIGS. 1–3 and 5–6 show portions of the replacement head in phantom lines. The portions shown in phantom lines form no part of the claimed design.