I assume you're talking about the cone-shaped metal piece at the end of the chain that covers the horsehair. Your best bet would be, since you live in Scotland, to check with various Highland outfitters/Rental Shops as most probably have a small collection of spare parts. Don't ignore the so-called Tat shops on the Royal Mile, they probably make most of the fittings in Pakistan anyway and could surely find an exact duplicate. There are also tassels available on eBay, the horsehair color may be wrong but you can just switch the metal thingy. www.landmhighland.com does to sporran refurbishing, any shop which sells L&M sporrans should be able to point you in the right direction.