Hello, Pretty straight forward question I suppose, but I have a Thermo-Price WC-27 Wood/Coal furnace and I replaced one of the gasket doors last year with a 5/8 rope gasket but it doesn't seem to be sealing properly, so I'm assuming I need one bigger but unsure what size. I have looked online and in my manual for the stove but can not find what size I actually need. I would appreciate any help. Thank you!