coloradosky

I recently purchased a Singer 27-4 treadle SN D905121. I used the machine a few days ago to make a fly cover out of fine netting for my sister's horse. The stitches were uniform and the tension was good. The following day I sat down and stitched a piece of cotton. When I examined the stitches the top thread looked beautiful however when looking on the underside the top thread just hung in huge loops and the bobbin thread could be pulled out with no effort. I readjusted the tension several times, changed the needle, took the tension apart and cleaned it for the second time, took the shuttle apart and cleaned it completely inside and out. There was only a very small amount of lint removed from the inside of the shuttle. I downloaded Miriam's "Has Anybody Got Tension Problems" and Thepolyparrot's "Getting Perfect Tensions" along with others. I have worked on this problem most of the afternoon today and finally examined the needle plate and felt a very small burr. I removed it by using a small fine file and used a pointed file and went inside the hole to remove any burr from this area. Reassembled the plate and pulled the bobbin thread up thru with the needle thread before closing the cover over the shuttle. Did a sample and the stitches were beautiful. Thinking I had found the problem I did the happy dance. Played around with the machine and this time I pulled the bobbin thread up thru the normal way. Sewed again and the stiches were back to the loops. I removed the round needle plate thinking I might not have gotten the burrs smooth enough in the area around the needle hole. I used a soft sanding stick and very gently smoothed some more, checked the hole again for burrs and reassembled the needle plate pulling the thread up before closing the cover over the shuttle - stitches were perfect. Later I ran out of bobbin thread, filled it and stitches were bad. This time I removed the screw from the needle plate and just lifted it and tightened it back down without acturally removing it, pulled up the bobbin thread and closed the cover - stitches were perfect again. I have tried leaving the cover open over the shuttle and bringing up the bobbin thread this way and then closing it and the stitches will be bad. Does it make any sense that I get good stitches after merely removing the screw from the needle plate, lifting it slightly, tightening it back down, bringing up the thread and then closing the shuttle cover? Any ideas would certainly be appreciated.