I am in the process of rejuvenating one of my Bolens Ride a Matic garden tractors. I need a cork gasket for the petrol cap which I hope will clean up to be re used again. Where do you get your gaskets from. I can either have rubber or cork as a gasket. The outer dimension is 4cm and the inner dimension is 3 cm. I could buy some cork and make my own gasket using the original as a template. Any help would be greatly appreciated. Thanks.