The Xpel headlight film that came with my CDI became discolored to I removed it. Film came off fine in one piece. But there's some adhesive residue that is proving to be particularly difficult to remove. Xpel says to use thumb and maybe some alcohol or other adhesive remover, but that's not working.

Any thoughts as to what method and/or solvent to use?

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 160k miles
06 E320 CDI "Rutherford", Black on Tan, 180k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 79k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife