An image forming apparatus having a pickup roller rotated to pick up a printing medium. Each spiral flow cooling circuit includes two adjacent channels that twist about each other in a radial direction of the blade to form a spiral flow path. The sheath may also include at least two distally extending arms connected to the circular connecting portion and a ring connected to the distal portion of the at least two distally extending arms. Withdrawal of the poppet valve head from the seat opens the firing chamber to communication with an intake or exhaust manifold runner in the engine head. Associated methods are also described. Further features are testing services and operating system on the new blade and cyclically shifting services through the blades.