Sometimes wires in vintage radios had natural rubber insulation. This insulation dries out and hardens over time. If the wire is not disturbed and it’s not carrying high voltages or in danger of touching the chassis, it’s ok to leave it alone. However, if they do have to be moved and they are liable to cause a short circuit and damage to components, it’s a good idea to replace these wires. If there are only a few short lengths of wire to replace, I will include those as part of the antique electronic restoration. But if there are more, then there will be an extra charge for the extra work.