To the guy experiencing rudder problems that posted in another online sailing forum...
I battled with the same issue for a couple of years. The problem, despite having all new H18 rudder gear, is that the plunger rotates forward and squeezes out from between the casting and the cam. There was a issue with some of the castings, and lubing and replacing the cam, plunger, spring, etc, won't solve the problem. I forget now if it was the dimension from the cam axle to the plunger, of if it was the actual recess for the plunger that was the problem.
It's a frustrating issue, with no evident repair.
Connect with your dealer and see if you can get a replacement.
Hope that helps!