I'm sure this one was a problem to who owned it. it was way to clean, I had problems adjusting the dails, until I read the book..
I see metal dogs new from $4 to $12, but these work and where free... I have been piecing blocks on this one all day , and no problem. I think they would be a good machine, but not for a beginner
as soon as it breaks , it will get tossed