3 choices, Buy a new Pro-Jump one http://www.pro-jump.co.uk/pp/ProJump-Spare-Parts/Adult-ProJump-Parts/Rubber-Sole.html
A Jason MK3 hoofy http://www.projumpforum.co.uk/index.php?topic=3132.0
Or make your own http://www.projumpforum.co.uk/index.php?topic=1261.0
Hellooo DC! 7's don't have the bolt on hoofs. Meaning you can't just attach the PJ spair rubbers, or the MK3 hoofies. And if the hoof is damaged or ripped you cant just cover it with a tire sock.
I'd suggest 7 leagues london. Search it. They have a website with contact details and do have spairs. Altho, 7's hoofs are not cheap @£30+ a pair. You could switch to hoofs from another brand like projump and then do the things DC suggested
I'm pretty sure PJ parts fit 7's