Even though you bought from a private party the larger manufacturers may still give you phone support at no charge. Handiquilter and Innova will definitely help walk you through issues on the phone. Gammel may as well as A1, APQS, and Nolting. You have nothing to lose by trying to call them. They all have 800 numbers. Thread wrapped around the hook seems to me a pretty easy issue to fix with the help of a tech walking your through it on the phone. You may have to reset the timing which, while time consuming is relatively easy.
I don't know what would be involved in resetting your robotics. That too, may be easily resolved having someone walk you through it on the phone.
I would try that before taking the machine head off the to be serviced.