Towa gauge--well worth the $$. I check every bobbin in insert even when there is some consistency in my winding them after 5 years. But changing thread does make a difference. Also, my tech said on my long arm that if you set the top tensioners about in the middle (if no # then where they are level with the screw)its usually the sweet spot--little adjustments from there. Most of the tension adjustment on long arms is done on the bobbin case. Definitely check for a FB page for the brand you have--other owners can be so helpful.