Ugh, that's such a frustrating discovery! I had the same thing happen with a cracked lid on a storage tote, and it drove me crazy until I coated the whole rim with a thin layer of food-grade silicone grease. That fixed the seal instantly and saved my whole batch of kitchen scraps. Now I check the gasket every month with a flashlight, just to catch any tiny splits before they wreck the anaerobic process.