TNcycling

Thank you for your help. I ordered some Ballistol lubricant. It should arrive soon. The knob is a good candidate for 3D printing.

Thank you all for the helpful videos and recommendations pertaining to operating my Pfaff 138. I was able to back off the bight control knob about 1/2", but I cannot pull it off the shaft. Something is holding it, perhaps a key of some sort? I have removed the set screw. The control knob freely rotates within limits because I don't want to damage the long spring on the back side of the knob. I also don't want to break the knob by forcing it off the shaft. The shaft itself is stuck on a zigzag stitch, but I am putting off fixing the shaft until I get off the knob. How do I remove the knob off its shaft?

Thank you. Yes, it must have been a safety check.

I have an original instruction book. I also have a spare parts catalogue. I don't a service manual. The link to the service manual does not work. It has sat for a long time. It is a Pfaff 138-6/21-BS. The SN is 139887. I was able to loosen the screws and turn the hook and adjust it. I first tested it by hand manually. Then I tried the motor. It makes a beautiful zigzag. It is also extremely fast. The video that nejcek74 provided describes the problem. The bight control knob is loose. I was able to free the bight set screw. The knob partially backs off the shaft, but it is still stuck on the shaft. The shaft is frozen as described in the video. I will try to get anti-seize lubricants as Hans suggested and proceed as he suggested along with the description in the video.

Thank you Hans, The hook is almost 180 degrees out of phase. I loosened the 2 screws that are in the video, but I cannot turn the hook. I think that it is stuck. The bight control knob that controls the width of the stitch is very hard to turn. The knob has a set screw, but I cannot loosen it because it is also stuck. The widest setting on Pfaff 138 is 6 mm compared to 4 mm on the Pfaff 30. I assume that 6 is the proper setting to adjust the hook. Thank you, Doug.

I have a Pfaff 138 sewing machine. The hook is way out of adjustment. I have been unable to find any service manuals for the pfaff 138 machine. How do I adjust the hook?