Hi! I have had my HQ Avante 18 for over a year now and just love it. However, I have continually run into this problem. I clean and oil my bobbin case (with a drop of oil) after every two bobbins, but after each time that I oil it, I have tension issues with birdnesting underneath and it always takes some time to get the tension correct again. I have not touched the top tension, so I don't understand why this happens. When I ask others about this they don't seem to have this issue. Any suggestions?