And I was taught an *awesome* way to get rid of 
it!! Take a blank piece of douga-paper. (Everyone 
must have at least one of these? ^_^)  Then cut a 
long strip off the paper - best to probably keep 
it at least one centimeter wide, but you can play 
with the width to see what works best. Then slip 
the strip of paper between the layers to the 
place where the "oily" bubbles are hiding. (If 
you cut the paper narrow enough, you can usually 
sneak it around the places where the cel is stuck 
and thus not worry about damaging the stuck 
layers.)

Just watch!! As you move the paper thorugh the 
bubbles, they'll disappear. . . I've never seen 
any come back after doing this either. (Doesn't 
mean they won't, but just that I haven't seen it 
yet.)

It's like magic! ^_^   I wish I could remember 
who to credit with teaching that to me since it's 
an invaluable trick! ^_^

Many Sharp Smiles,
--Drac