Is there a chance your feed-dogs were inadvertently dropped without your knowledge? If you continue to have this problem after checking threading paths and bobbin insertion, you may want to take it back to the store for an exchange because it may not be something you are doing. Dealer should either resolve quickly or replace the machine with a new one. Also at any point did you remove the bobbin CASE? if so, that can be finicky to get back in just exactly right and it is difficult to tell if it isn't in right because it looks as if it is. Last suggestion is could your needle be blunt or bent and is it inserted all the way up? Let us know what problem is when you find out.