I totally understand. I had one like that too. Every time I had to re-thread it or change the bobbin, it would act up. I would re-thread and re-thread and re-thread, the same way each time, and eventually it would start working. It nearly drove me crazy until one day, it did drive me crazy. I got in the car, drove to the nearest sewing machine dealer, and bought a new one. I didn't shop around, I just bought one, and I've lived happily ever after. I had the old one serviced, and I keep it on a shelf as a spare. So far, I haven't used it since that day.