Hello everyone, I have a 1945 singer 42-5 machine. I am getting fantastic stitches on heavy fabrics and the such. But when I switch to even a single layer of 5-6oz veg tan with a 277 thread and a 25 leather point needle it goes haywire. The thread starts to almost come unraveled rite above the needle eye and it will only lay thread on top of the workpiece. I dont know what I need to do to correct this. I use the same size needle and thread on canvas or fabric and it's great, but when I switch it goes bonkers. Any help would be greatly appreciated.