lock ratchet by moving the hook-driving shaft to the right until it clears the hook-driving shaft lock ratchet, thus allowing it to drop from the shaft. Arm Shaft Connection Belt Timing Collar and Hook-Driving Shaft Ball-Bearing Collar The arm shaft connection belt timing collar and the hook-driving shaft ball-bearing collar are the initial timing points on the machine. Do not remove these parts from the machine. In machines fitted with cast iron bushings, the timing collar will fall off as the shaft is withdrawn. Hook-Driving Shaft The hook-driving shaft (figure 4-6 [N]) transfers power and motion to the units attached to it. To remove the hook-driving shaft, you grasp it and withdraw it to the right. Bobbin-Case Opener The bobbin-case opener (figure 4-9 [D]) acts as a lever to pull the bobbin case back from the throat plate. It allows the needle thread to pass between the bobbin case and the throat plate. To remove the bobbin-case opener, you unscrew the adjusting screw (figure 4-9 [E]) and lift it from the hook saddle assembly. Hook Saddle Screw The hook saddle screw (figure 4-6 [B]) holds the hook saddle assembly in place. Unscrew the hook saddle screw to remove it. Hook Saddle Assembly The hook saddle assembly (figure 4-6 [U]) forms the lower half of the stitch. To remove the hook saddle assembly, unscrew the hook saddle screw and loosen the hook saddle pinch screw (figure 4-6 [A]). Draw the hook saddle assembly slightly toward the operator, slide it to the left until it clears the center hook-driving shaft bushing, and withdraw it from the machine. This completes the disassembly of the sewing machine. REASSEMBLY Before reassembling the sewing machine, you will need some grinding compound to smooth parts that may have surface rust or small burrs. A small amount of grinding compound on the surface is sufficient. Rotate the two parts until they move freely. You will also need some 10W mineral oil to lubricate all moving parts. After you accomplish these tasks, proceed as follows to reassemble the sewing machine. Hook Saddle Assembly To replace the hook saddle assembly, hold it in an upright position with the saddle clamp facing the bed of the machine; then place the saddle clamp on the edge of the center hook- driving shaft bushing. Swing the hook saddle assembly toward the bed of the machine and slide it to the right and into place in the opening in the casting. Hook Saddle Screw With the hook saddle assembly as far to the right as it will go, replace the hook saddle screw and tighten it. Bobbin-Case Opener Lift the machine to the upright position. Replace the bobbin-case opener so that the curved end points toward the bobbin case. Replace the bobbin-case opener adjusting screw and tighten it. Hook-Driving Shaft Tilt the machine forward. In replacing the hook-driving shaft, you should note that it has five splined grooves. One of the splined grooves is located at one end of the shaft. Insert the end without a splined groove into the right hook- driving shaft bearing. Hook-Driving Shaft Lock Ratchet As the hook-driving shaft is pushed toward the left, or face, of the machine, replace the hook- driving shaft lock ratchet so that the flange with the setscrews faces the left of the machine. Feed-Driving Connection and Feed-Driving Crank Hold the feed-driving eccentric with the flange and spring to the right; then place the feed-driving connection, with the feed-driving crank attached, over the cam on the feed-driving eccentric. Be sure the oiling felt faces upward and the crank is toward the operator. 4-27