A roof seaming machine has symmetrically arranged forming rolls and a reversible permanent magnet motor for operation of the machine in either a forward or reverse direction. Adjustable linkage connects the forming rolls with an articulated handle for moving the forming rolls relative to a drive wheel which propels the machine and which is adapted to be disposed on the opposite of a seam from the forming rolls. A reversible switch is connected to energize and deenergize the motor, and a directional switch safety guard is associated with the switch to limit its movement between an "off" position and either one of two "on" positions, depending upon the positioning of the guard.
