Well, I started to post on this question, but somehow lost the post. So if ya'll see a partly completed pos,t it was me -- Woops... ,
I do not know what set with a body gripper you are having this problem with, nor do I know the laws regarding body grippers you have to work within. Certainly adjusting the trap as noted in the archives may help. So my answer may not be of help to you. I hope that it is.
When I make a body gripper set partly submerged in flowing water I make a single pole set. One of the reasons I use this technique is that it is less likely to accumulate debris and flotsam around the triggers, which increases resistence to the current, and results in false fires.
A single pole set is constructed by bending both the springs back in the direction of the dogged jaw when the trap is set. A single pole is driven down through the two eyes, and into the bottom. The dogged jaw should be the closest to the single pole. Both the dogged jaw and the free jaw will be 90º to the surface of the water. Once the trap is stabilized, slide the complete firing mechanism up above the water surface. The trigger wires should be parallel to one another, parallel to the surface of the water, and high enough that they will not be engaged by the critter until he is well into the trap.
The "high & dry" trigger wires, being above the surface of the water are not subjected to the pressures of the flow, and do not collect debris.
If the trap does not adequatey stabilize with only the single pole, it may be stabilized using
other methods. For instance, a stick may be run diagonally between either of the outside corners of the trap; or push a stick straight down under the trap, and squeeze the lower springs around it.
Another advantage to the single pole set is that it fires from side-to-side. The usual jaw motion of a body gripper can knock a swimming animal up and out. Not so when the trap fires side to side -- it is deadly.