Suntour symetric shifters question

[cromoly4130]

New to the forum and it looks like a lot of helpful info here.
Now that that's out of the way,
I have a problem locating a part for my down tube shifter. It's a flat washer that has a small hook or tab on it that sits inside the shifter. The hook part has a crack and is starting to break off. Does anyone know where I can get a replacement part for it?
Thanks

[cromoly4130]

I had no experience with this type flat washer previous to finding it in the shifter. The part I'm looking for would be a tang washer.