Daiwa UK would be a good place to start. The 7HT is a current reel and they'll have all the parts in stock. The phone number has been posted on here several times over the last year or so. If you can't find it, Blakdog will know the contact details.
It would be easier if you had the schematic so you can quote the part numbers.
Go direct to daiwa (with part numbers and credit card handy) ... 08450 603603. If your reels are earlier japanese made reels be careful when ordering parts. The normal 7HT is no longer made in Japan and there have been changes to some of the parts (even though they still carry the original part number). Not sure on all the parts but I know for sure the drive shaft and the pin it sits on is now taller so if you need to replace either a drive shaft or a set plate on an early reel you will need to replace both. If in doubt ask when you ring up.