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kohler toilet "canister valve" doesn't seal
(imgur.com)
Start with the gasket. I replaced one in my Kohler toilet. Easy and cheap. You have to remove the cylinder to replace it, so you'll have the opportunity to inspect it for damage.
Ok yes replace the gasket but it looks like the chain is wound up on the lever and needs to be unwrapped to make the seal.
The twisted chain was 100% the issue. I'm so amazed that you were able to catch that in that shitty video I uploaded above. Thanks again so much for your sharp eye!
No problem glad to help
Home Improvement