Jon thanks, you gave me that knock in the head, that i needed..
I got it out last night playing with the dogs, they move just by pushing with a finger ???
It's a guide ofcousre at the end of the feed dog and is a part of stitch lenght, I see that plain as day now, because of the tightness in that area and there is a post there that the piece sits on, that post looks as if it's the guide
but , That screw is another part ?? LOL... I'l l put that in tonight and post pictures, since there is so little info on standards on the net ..