Piaggio Vespa Clustershaft (Input Shaft) Tab Washer PX, T5, Cosa
The washer is fitted to the outside of the crankcase. The washer and tab secure the shaft to the crankcase.
Make sure you have positioned the Tab and washer correctly, tightening it in the wrong position will cause the tab not to fit.
Comparison No. 016612 (PIAGGIO)