I also have a Brother CS6000i machine. I used it to make over 100 denim quilts in the past 3 years, plus other sewing, both clothing and quilting, including Crazy Quilting with velvets and silks.
I thought I broke it. Took it to a Brother dealer who tried to sell me another machine.
When I took a Singer that I inherited, for service at an old style service center, I mentioned the Brother. I was told "Bring it in. The estimate is free." They fixed my Brother CS6000i for $89. It needed adjustment, that was all. Before you give up on your current machine, try a GOOD Sewing Machine Service Center.
I highly recommend the Brother machine, though.