agreed, solvents can work, but sometimes they take repeated applications, and days to finally soak in. I've heard a mixture of automatic transmission fluid (or power steering fluid, smaller bottle with twist off cap) mixed with acetone (nail polish remover) 50-50 will work as well as any of the other branded solvents. The thing with solvents is, you either need to soak a part in them, (not decals) or keep brushing it on, as the evaporation of the most volatile ingredients will mean you need to keep flooding the area. Patience and persistence! And not too much force, mostly just keep trying to rock it back and forth.