Not sure about what you are saying is fitting your 7700.....You do need the correct holder for your 7700.....and you need the 7mm feet..... however, I have heard that snap on 9mm could fit our 7mm machines. I have both 7mm and 9mm machines and am worried I will get feet and holders mixed up. So I bought the foot carryall cases for each of my 7mm and 9mm. Love my Janomes.
Your holder and foot will turn up, I'm sure. Best wishes.