I think you are confusing the sealing rings at the bottom of the cylinders with the paper gaskets that go between the outer diameter of the cylinders and outer mouth of the crankcase. When you replace them use an ethanol resistant material instead of the granulated cork rings which are NOT ethanol resistant. The Spares Scheme can supply them. The paper outer packings can be replaced with a THIN SMEAR of silicone mastic, but the paper ones are perfectly OK.
Brian
