Stinky Old Fish is correct. You have mixed brands of parts in the photo. The slot in the washer allows you to stick a pointed tool in there to turn the cone. That washer is not correct for that cone. The correct cone has 2 radial slots, like screw driver slots, that cross over the washer slot. One of the 2 radial slots is always accessible. This was designed so you could fine tune the cone position without having to back the locknut way off to get access to the cone.
Here are a few from my parts bins.
The cones on the left work with that washer.
The sloted washer is huge to try to keep some dirt out. The cone is smaller and it needs some help. Compared to the Schwinn style that uses a huge cone and small washer.
The cone on the right takes a different washer (more a dust cap really) that keys into the cone and extends over the shell, then a second regular lock washer and then a nut. My Tunturi has this style. You can loosen the locknut and turn the the cone with the cap. Then tighten the locknut. IMO, best design for 1 piece cranks. The 4th photo is of my Tunturi. The big chrome cap slots in the cone and covers the entire bb shell and serves as a cone extension to turn by hand. Its a far better system but Tunturi still buggered it with an undersize bb shell, smaller cones and bearings and a lock nut you can't touch with a wrench. None of my pin tools would hold tight. Grr.
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