Welcome from OK. I have a pfaff grand quilter and all of the advise that has been given here has been really good. My thread problem was solved by switching to a better grade of thread. The first place that looks like your thread should go under is for winding the bobbin only.....If you put the thread under it and quilt it will unthread the needle every time you cut the thread. My stitch regulator never would work but with a little practice you will do fine free hand. If you want the page of the manual on threading the machine I would be glad to try to e-mail it to you. Just pm me. Hope you get it solved!!!!
BettyBoop