plate 27 at the upper side of shoe plate 25 is a thin metal plate on which counterweight 26 is slidably movable and has been described in greater detail in u s pat no 4 228 620 plate 27 may be secured to shoe 25 by a pair of screws 93 also serving to retain pad 22 to the shoe pad 22 preferably includes an upper essentially stiff metal horizontal plate 94 carrying at its underside a pad 95 formed of rubber or other elastomeric material and suitably adhered to plate 94 screws 93 extend vertically through plates 94 25 and 27 and have nuts 96 at their upper ends attaching these parts tightly together a similar but shorter additional screw 97 attaches plate 94 to plate 25 at a central location with that screw being threadedly connected to plate 25 and having a head at the underside of plate 94 as seen best in fig4 and 7 body 11 of the tool carries at its underside two forward bearing elements 98 extending along opposite sides of the body and two similar rear bearing elements 99 these bearing elements 98 and 99 may be formed of thin strips of an appropriate low friction low wear resinous plastic material each of the four bearing elements has a horizontal undersurface slidably engaging the horizontal upper surface of wear plate 27 near its opposite side edges to apply downward force to plate 25 and pad 22 from the body bearing elements 99 and 98 are secured to body 11 of the tool in fixed position relative thereto in any appropriate manner counterweight 26 is slidably received within the lower.