A few weeks back, when trying to refit the v-brakes on my son's MTB after taking the wheel off, I shattered a threaded plastic washer on his Shimano brake & gear lever (ST EF500).
I call it a threaded washer, but I'm not sure of the part name. It is the black plastic item I've ringed in red in the picture of the non-damage brake lever:
I can't identify the part to get a replacement. I know I can get a pair of replacement levers for about £25, but I'd rather not spend that when I just want the plastic washer thing. I've searched for 'Shimano plastic washer', but that returns part for fishing rods!
Can anyone tell me the name of the part, please?