I was pretty excited with this purchase Master Series "Inhibitor", and it looked to be of excellent quality at first inspection. However it quickly became apparent that one of the seams between two joined parts is leaking substantially. I believe the gag is made of silicone (definitely isn't latex), but I'd like some way to find out for sure, then find a suitable material to seal the gap. I need it to bond properly, handle mild stretching from inflation, and be more or less nontoxic when cured.

I don't think this is something I'll be allowed to return or replace, and even if it is, I think I'd rather repair than try my luck replacing it. Any ideas?