Preparation and following the steps for curing the epoxy are Critical for long term effectiveness. I realize this isn't part of the crank chamber, but tranny fluid is really stinky. First moped I bought had a crack sealed with epoxy. Guess what happened when I got it running really well? Blew out the epoxy.
My e50's drain plug stripped. So I epoxied that sucker from both sides of the case. Never leaked. (edited)