They have a chat line on their website. Maybe you could start there & ask if they have any free, online tutorials or suggestions for getting the back straight before you start quilting. Here's a link to their site & you will see a round icon with a telephone in it & the one above has a smile (bottom right hand corner). The one with the smile is the chat line. Hope this helps you.
https://www.graceframe.com/en/machin...one-hoop-frame