from another board, you can try this to see if it helps or not
It seems that most users will backlash at the start of a cast, more so than at the end. Therefore, many users were not able to master the mag only reels. Here are a few tips. First off, they set up differently than most reels. To set the reel, you need to remember to always start with the mag dial at zero. Anytime you change baits, and need to reset the reel, you need to turn the dial back to zero.
With the dial at zero, set the tension knob to a point that when you depress the thumb bar, the bait will not drop in freespool until you give the rod a slight shake. When the tension is set right, you should be able to get the bait to fall a foot or two, in freespool, by shaking the rod some. Once you have the tension set there, DO NOT set it any tighter. Setting the tension any tighter than that will cause the spool shaft to drill into the tension disks. So, when you get the tension set there, turn the mag dial up to where you think it should be. New users, go ahead and set the mag dial to 10 and then back it off with each cast until it starts to feel like it might be close to backlashing, then turn it back up a bit.
That will be your setting for most conditions. Turn it back up a bit from there to cast into the wind. As you master the reel and get better at thumbing the spool, you can set the initial tension looser, just remember, the tension is not a brake, it's a setting for spool tension and you will damage the reel if you run it to tight. That goes for all reels. The reason you need the mag dial at zero before setting tension is that you set the tension by watching the fall of the bait in free spool. If the mag dial is turned on, it will slow the fall of the bait while trying to set the tension. You will then set the tension based on that slower fall rate and will backlash the heck out of it on your first cast.