Regarding the tension, maybe give us a few details of what makes you want to throw it off the roof.
Also tell us:
What thread
What needle.
What have you tried to fix it.
Did it ever work the way you wanted it to?
I wish you lived closer to Washington. I'd offer to come help you with the tension part -- at no charge. I could do the rest, but won't because then if anything goes wrong it's MY fault ;-). I am very technical and it's really helped with troubleshooting sewing problems as well.
Sometimes using the right needle changes EVERYTHING "tension"-wise.
Sewing machines, whether they're quilters, domestics etc are all basically similar. Any sewing machine repair worth its salt can adjust them. Try calling your local sewing shop.