Hi John and welcome to Beoworld !
If I understand your post correctly, you need a set of drivebelts for the cassettesection in a Beocenter 7007. I can supply those. I may also be able to help you with DIN plugs and/or cables to your specifications. PM me for details.
The Beogram CD X springs to mind as a suitable CD player, or maybe a CD3300.
Your local dealer should be able to supply you with a suitable FM arial. The tuner in your Beocenter is very good and sensitive so any arial will probably work.
Martin