Brother LS-1217 Mechanical Sewing Machine "vertical hold jumps" Questions

...and it breaks or worse the needle breaks. I want to throw it out in the yard. The thread stands vertical. Its like the tension spring holds for a few seconds then tightens to 10 when it's only on ...

...hold the hole vertical, and inserted the front-end piece. Then I dropped in the discs one-by-one. Finally I screwed down the brass fitting and reassembled the control. The difference was amazing! If ...