i've got stock parking sensors on my rear bumper and on one of them, the rubber ring that sits inside seems like its coming out slowly. It is not as flush against the sensor as the rest of them are

If i take a credit card or something and push it then it seems it might go in. I dont want to damage it either.

Has anyone got any experience with the ring rubber? how can i get it back into its position properly?

thanks

 

If you are still under warranty, I'd let the dealer do it, rather than fool with it and make it worse.