Is it tensions or timing? Often people try to tell me what is wrong with their machine as either tensions or timing. Sadly, too often what they describe is not what they call it. Here is a simple way to recognize the difference: If stitches fail to form it is a timing problem. If excess threads appear above or beneath the fabric, it is a tension problem. Timing requires the feed dogs, the needle bar, and the hook assembly to properly work together. Tensions require proper threading and balancing of the resistance on the upper and lower thread sources.