A new spring clip? They sell them at Autozone. Nasty little things to replace - you need spring clip pliers and lots of patience. Prepare to curse often when they ping off into places unseen.

 

Missing spring washer.

 

I think it's called a D-washer

 

I just purchased four of them at the dealer. The invoice says 'spring washer'. They're not that difficult to install. I had them all installed in 5 minutes.
part # 50912-72
They're a little pricey in my opinion $2.92 each
$12.50 total (with a 10% discount)