The long arm I previously owned was a Tin Lizzie 18. I rarely had tension issues and I used several different brands of thread. However, whatever brand of thread I used, I use it on both the top and the bottom. Maybe this will help you somewhat. I also used to have my tension tighter in my bobbin than what was suggested. When I held up my bobbin case by the thread, (with the bobbin in it), it did not gently go down like a spider, like they sugest it should to have the right tension. My thread was always tighter. Maybe you could buy a new bobbin case and try that. But definitely try using the same thread on top and on bottom to try to alleviate some problems. I never had tension problems with my Tin Lizzie, so sorry I don't have any other suggestions.