Best Way To Remove Paint From Rubber????

Previous owner of my '69 Dart had a Maaco paintjob put on just before he sold it. Not my color choice and the bodywork isn't up to the quality I want so it's got to be repainted after the bodywork is brought up to snuff.
Trouble is, he left the body-to-bumper cushions (rubber spacers between the body and the bumper underneath the rear taillights) on the car when it was painted and didn't mask them off.
What's the best way to remove paint from rubber without damaging the rubber? I want to try to use the existing parts rather than buy new ones.

Thanks!!!