i used to work in a decal shop. we did great dane semi trailers, cop cars, traveled around doing gas station awnings. the trick to removing a decal is heat (and patients). you don't want to get it so hot that it melts. take a propane torch, hold it about 6 inches away from the swing arm. move it rapidly across the decal. you will see condensation appear on the swing arm. keep heating until the condensation evaporates (keep the torch moving). once it is warm (not hot) you can use your fingernail to remove the decal. if it doesn't pull easily apply more heat. if you start don't be afraid to add heat as you go. once its off some goo gone will get the adhesive off. never had much luck with a heat gun but you could give that a shot too
