OoooOps, pressed too soon, I have seen a very long lived repair done with Silicone Acquarium sealent injected in using a small syringe into the gap, after carefully removing as much of the existing sealant as possible, and then drying the tankard in an oven that has been heated and then turned off so that it is warm, then leave the tankard in it for an hour or too, the silicone will stick to clean glass well.