This is an industrial machine that is used for upholstery work. It had a bad crash when one of the set screws that hold the bobbin shaft drive gear backed out and caught on something. This caused some damage, which has been repaired, but now it intermittently fails to pickup the bobbin thread, causing it to skip a stitch. Sometimes it skips one in ten, but sometimes it will go for 50+ without skipping. I think there is still a slight problem with the timing, but I need some help. .