The answer to 'leak repair won't flush' is that a leak in the plumbing system can prevent proper flushing of the toilet. This is often caused by a leak in the toilet tank or a problem with the flush valve. Symptoms may include water draining slowly, the toilet not fully flushing, or the tank taking a long time to refill.
To fix this issue, you'll first need to identify and repair the leak. This may involve replacing the flush valve, tightening connections, or addressing other plumbing problems. If you're not comfortable doing this yourself, it's best to call a professional plumber who can properly diagnose and fix the problem.