Well, I'm definitely not going to take the lens apart and risk damaging it when I can just return it, I have no experience with lens repair. Also, I've read that there's always a chance the mold will return. As for having it cleaned by a professional, unfortunately I think it would cost more than the lens itself at this point, not to mention the turnaround time might be extensive. Fortunately I bought it from a very reputable seller (I always do), and he's already said he's sorry for the trouble and will refund me. If I'm lucky maybe he can find a replacement lens instead, that would be ideal. It's not like these things are hard to find in Tokyo after all.