I have a 1957 WD45 and on the right hand side there is a cap on the right frame rail where the belt gear assembly is supposed to go. You can pry the cover off with a screwdriver and in the casting there is a 1/4" thick x 1/4" wide gasket set in the recessed groove. The gasket is shot. Any ideas where a fella could get one. I have tried to find gasket material 1/4" thick, but no can do.