I recently bought a huge lot of older Lego. It contained one of the big trans-blue panels (http://www.peeron.com/inv/parts/2408) from the 6991 monorail set with the sticker on it. The sticker was already pretty damaged and looked pretty unsightly, and after the obligatory trip through the washing machine, it was a complete loss, i.e. most of the upper layer of the sticker had come off.
I'd like to use that panel as a spare for my 6990 monorail, but the sticker apparently was applied with some really strong glue. Neither the trip through the washing machine nor my attempts with water and any mild cleaning fluid I have could get rid of it, in fact there's still most of the paper base on there, just the upper part of the sticker with the actual printing came off.
Usually, I resort to alcohol/ethanol-based solvents when removing stickers from even surfaces like glass or metal, but I'm hesistant to do so in this case because I fear that the solvent could damage the plastic.
Has anybody ever faced a similar problem, or knows what I could safely use to get the remains of the sticker off without damaging the panel?
I don't want to resort to strong scrubbing with a hard brush either, as I guess I would end up scratching the panel.
Thanks in advance!
(I hope this hasn't been discussed already, but my search returned no matching results.)