Sorry you're having trouble. Sometimes the machines just aren't adjusted right from the factory - I had a Brother that drove me crazy with broken threads and bent and broken needles til I went back to the dealer with it for a class and they noticed that it didn't sound right. Back it went and got readjusted.
I always just use Schmetz topstitch or quilting needles 90/14 in my GQ and have no trouble. However, I did have a learning curve with it when I broke a lot of thread and needles. I learned to slow down. Once I found the speed my machine liked to travel at, we work great together.
Good Luck.