My bug shield had little self-stick silicone rubber bumpers that where attached to the back of the bug-deflector.
I would guess that you could find some similar self-stick bumpers in hardware stores and home centers where they are sold as non-skid bumpers for lamps and vases, etc. I have even seen them used on the backs of cabinet doors to cushion the doors from slamming shut.
The are about 3/8"-1/2" in diameter and about 1/4" high.
...Rich
