Fatire, (is that a reference to mountainbiking?) Here is a drawing of my CB (sorry it's so fuzzy, I'm pretty fuzzy too).
There is a well known problem with the slack uphaul or downhaul falling to the side of the CB and jamming the operation of the CB. When this happened to me I could usually free the board by pulling hard on one of the control lines or pushing a metal rod in the downhaul hole to force the board down.
I fixed this problem by taking the board out, with the boat careened on it's side, and routing the uphaul and the downhaul lines through a circular cotter pin (such as used on a clevis pin) at the point where they cross paths. In this way the slack line was always supported and didn't fall to the side of the board. I can't think of any reason why you couldn't do this in the water! (The board is about 25 pounds).
Another solution would be to replace the wire rope control lines with 1/8" Dyneema. The line would be just as strong and stretchless but is less wide and should not get caught.
Now I have a 3 to 1 purchase on the downhaul, and a 4 to 1 purchase on the uphaul because the board occasionally sticks, perhaps the board's pivot hole is enlarging on the pivot pin and allowing misalignment.
But, I can't think of a way to work on the CB without releasing the pivot pin and pulling the board out...