Hello, I've been unable to locate any of the black plastic approximately seven inch-long retainers/sleeves that clip over the windshield wiper arm and hold the windshield washer hose in place. My car is a '90 convertible and the original retainers are splitting; one has fallen off and the other is about to. Can anyone please direct me to a source for these retainers? I want to keep the car as original as possible. Thank you.