I'm hoping that someone can help me tune my bartacks. The top side looks pretty good, but the bottom/bobbin side shows frayed thread sticking out. It looks like the thread in the bartack is getting torn by the needle (maybe?). It holds fine, but doesn't look good, and since we're selling at a premium, I'd like everything to be really clean looking.

I'm using a Juki LK1900B. Tex70 bonded nylon on top and Tex45 bonded nylon on the bottom with a new Schmetz needle size 110/18 (DPx17 type). It's a 28 stitch, 10mm wide tack used for belt loops, but the same problem happens with a wider tack through webbing. I've slowed the speed down to 1400 stitches per minute. I've played with the tension a lot with no change to this problem (though I can easily cause other problems when the tension is wrong).

Any ideas what I should try adjusting next?