I do not have the larger sailing rudder. I have a pull system. I pull the toggle in one direction to raise or lower the rudder. There is no method employed to hold it in position. What happens as I steer the boat I cannot go straight. I go either to the left or right by twenty degrees or more. I want to keep the boat going straight, but it turns hard to port or starboard by too many degrees. If someone knows the answer, please let me know. Otherwise I will have to take it to the dealership.
I am not sure which style rudder you have, there have been several. My 2007 Adventure (single hull kayak) had the twist and stow style, which raised and lowered by a lever on the right side, and the tiller or steering lever was on the left. When I added the Island conversion with the outriggers, a larger size rudder was part of the kit.
There was a free upgrade to the pull style, where two lines, each with a T handle were installed, pulling on one lowered, and a cam cleat held the line, holding the rudder down. Releasing the cam and pulling on the other line raised the rudder. The two lines are on opposite sides of the cockpit. The twist and stow rudder came up on an angle, and twisted around, ending up laying flat on the rear deck. The newer style sailing rudder has the same two line control to raise and lower, but it rotates straight up when raised. If you have the twist and stow, there is a small thumbscrew that can be adjusted to help hold the rudder down, but too much and it is difficult to raise again. When you say "I pull the toggle in one direction to raise or lower", it sounds like you still have a lever handle, and not the two line setup. If that is the case, talk to Matt, he should be able to hook you up with the upgrade kit, the two line system holds the rudder down much better, for better steering control. It does involve drilling holes in your boat, but a "do it yourself" type person should be able to handle it OK. How far away is your dealer?