My G16 had this same problem, not only with the thumb grip but the same material wrapping the finger grip around front; the edges came loose and it was ugly. I've read that they just use double sided tape to glue those thin pieces on. I tried contact cement - fail. Epoxy - fail. Adhering to the rubber and the plastic is difficult. Just clean up the residue of the crappy adhesive tape they used and go commando! Holding the bare body isn't bad - this tiny camera really has no grip to speak of - its too small! I do love the performance though, and its not hard to carry around. Otherwise, I see various rolls of 3M tape on Amazon for around $15 - maybe there is something thin enough available there. And maybe a camera store has a fix that does not cost $100...