Dear Yoer,Good day to you !Firstly, we did not change the factory, and after checking our record, we found it’s only slight different on the drive depth & undercut, but it’s doesn’t make too much of a different between these two times shipping samples. They are almost the same.Could you able to show me some picture of the vinyl material with screw ? I try to catch more exactly on your meaning. Is that mean the undercut screws are not tight enough and will loosen after drilling on vinyl material ? Then we can see how to make it more better for your using. Anyway, noted that you are more satisfied with the 1st shipping products, we will check the production line and make it more closer to the 1st ordered.