Rubbing alcohol always seems to be the solution to things, but I haven't got any, or know where to get it (I'm sure fellow UK collectors will tell me that it's simple like going to B&Q or something!!)... 
Tried hot water soaking as suggested to me by someone, no effect unfortunately, but that bag is only for finding a solution, don't mind damaging it, thinking of pulling the zip off for my G3's bag (it's the taller style bag that accommodates the drainpipe filltube setup)...
