I was going to chime in again but Janey said it. That washer can be rotated 180 degrees from it's current orientation, and also flipped over and have two possible positions.
You should be able to tighten the clutch knob without the gib or stop screw hitting a tang/lobe, but when you back it off it the screw should then hit a tang/lobe and the hand wheel should spin independently from the machine.
Those tangs/lobes may be bent or they may have bumps on them. If bent, on the Singer machines I've worked on the bend of the tangs/lobes is away from the machine and towards the clutch knob.
I hope this all makes sense.