The three thumb screws lock against the projections of the T2 insert (#3) or the M48 insert (#4), depending on which one your setup needs. Loosening the screws gives you some lateral movement for alignment, but it is limited by the projection width ie if you rotate too far the screws will not be in contact with anything.
Perhaps you need to add a rotating ring?
https://www.highpointscientific.com/...components.jpg