tank to toilet gasket: workaround?

[Ombligo]

You may actually have it overtightened, which can cause a leak. There may be a small crack in the tank. The bolt washers may be bad. You need to find out where the leak is to know.

Put some food coloring in the tank, see where the leak is. Then decide what the best course of action is. It may be new washers, silicone sealent, flexsealing the entire inside of the tank, or replacing either the tank or the whole toilet.