Solvents for removing very old masking tape from front panels?

I use something available in the UK called sticky stuff remover seems to be citric acid based. I rub it on the label and allow it to soak for a bit, hopefully that softens the sticky enough to pull the paper off (very slowly) probably needs more than one/many applications to soften if very hard. Also WD40 softens the sticky and a few other solvents, I have recently tried http://consumables.com/Products/Sealants_2/Pvcu-Solvent-Cleaner.html (safety sheet on that page with its makeup) which also works but has some noxious fumes. as always test on a small area if the plastic/paint will affected by the solvent. After softening I try to use nothing harder than finger nails to remove the labels, can be painful and take a long time but the panel matters the nails can grow back the panel cannot. Then a final washing (rubbing with a paper towel dipped in solvent) with the solvent in use to get the remainder off. Note you need to be careful at this stage because the rag/paper can polish the surface of the paint/plastic surface. Dave Caroline