Go to Daiwa direct:
http://www.daiwasports.co.uk/contact/They are really good to send you out the part, provided it's still available, but most are, I was looking for a handle lock screw for a 18 year old Daiwa Regal-X 4550 BR recently, got in touch with them via their website and had the replacement in the post within a few days, free of charge

That's customer service as it should be, fair play to them
Here is the email address from the girl I was dealing with:
Helen_McFadyen@daiwasports.co.ukGood luck - Martin.