You might be very lucky and find NOS, but I suspect that is going to be hard too find, ebay...Swap meet. If your current one cannot be repaired by a friendly upholsterer check https://newtoncomm.co.uk/ you might be able to get some original reproduction vinyl to make up something. If you are not concerned with originality, then search for rubber boat trim. Often available by the Meter, wide variety of rubber trim in all kinds of shames and sizes. - Just an idea. Someone else here might have better advise!