Missing Headset Piece

[Brady Smith]

Hi all, 

A few weeks ago I took my Roadini apart and put it back together again in a successful attempt at getting rid of a certain noise of uncertain origin. But since, my headset, hitherto perfectly functioning, has started to come loose. In perusing the Riv website, I found the relevant schematic, and I'm missing part 2 listed below. I think it's a 1" by 1mm spacer--does anyone know for sure? 

Thanks,

BMS

[Danny]

It's a keyed lockwasher to fit into the keyed groove on the steerer tube. I just measured the thickness at 1.97mm. You can see the part you're after in this photo on Riv's listing (the second part from the right). https://www.rivbike.com/cdn/shop/files/hsfsa2.jpg?v=1775238285&width=2048

Danny
Madison, WI