An easy way to check if the Ackerman mechanism is set up correctly is to run a string out sideways from the 1/3 chord point of the centerboards and anchor it a good way out from the boat, set the rudders to a fairly hard over position, run a line exactly square from the nearest rudder to the sideways line and make a mark at the intersection, do the same from the farther rudder. The lines from both rudders should intersect the sideways line at the same point. If they do not,disconnect the tiller connector from one tiller and adjust one rudder until both lines do intersect at the same point. Measure the distance from the connector hole is from the pin. Take half this dimension and add it to each tiller to bring the pin to the correct location (it is a good idea to
make sure you get it in the right direction). A triangular plate picking up on the existing pin hole plus an extra hole on the tiller to prevent rotation would do this better than bending the tillers but make sure that the tiller pins remain parallel to the pintles in both planes.