Juki 1508 Help Help HELP HELP!!!!!!!!!!

[RocketmanMH1]

OK guys I need some help today.  I have a 1508 that sews wonderfully, slowly and at a high rate of speed as well, the stitch is nice and even, top and bottom are exactly the same. This is the first machine I have ever had that the bottom of the stitch looks as good as the top. OK here's the problem, when I backtac at a slow rate of speed, on the second or third stitch back, I get a loose loop on the bottom and the hook catches it and you know what happens next. I am very impressed with all other qualities of this machine and know there is just a little something I'm missing to get this worked out. Please throw those options at me!!!!!!

Thanks
Mike