I need to get a new sewing machine.... =(

Everything was fine until my sewing machine decided to stop working properly after I changed the spool of thread.. My upper thread tension knob now seems to be spoilt and I can't adjust the tension again..!! Arrghhh...

It might seem okay on the outside, but the inside of the belt band is totally messy! >< Looks like this pair of culottes needs to be thrown into my home-clothes bin. =(

Anyone knows how to repair the upper thread tension knob??