You should have 9 spacer washers. These are used in three places.
1, on the shaped top hat thing that you show on the dynamo shaft. These are used to align the pulley with the crankshaft pulley. often none here but could be two or three. then the inner fan belt pulley half goes onto the shaft.
2, in between the two halves of the fan belt pulley to tension the belt.
3, the unused spacer washers then are put on the end of the dynamo shaft onto the outside of the outer pulley and the spacer washers and pulley halves are tightened with the special nut.
Check the tightness of the fan belt by turning the engine over by hand and repeat the procedure and change the position of the spacer washers to obtain the correct tension of the belt, don't overtighten and make sure the pulleys are aligned.
If you are doing this you should use a new fan belt to make all the fiddling about worthwhile. Good luck.
