We have a pair of Outfitters bought in '06 that have many miles on them under peddle and sail. They have the twist and stow rudders. They have both, several times now, lost weather helm to one side or the other while under sail in heavy wind. There are two causes/fixes (don't know if this applies to other models):
1. In the water with the rudder down, see how easily the bottom of the rudder pulls aft. If it is not pretty tight, adjust the lines that control raising and lowering the rudder.
2. If the rudder is tight and won't drift back, adjust the steering control line on the side you lose helm to remove any excess slack (if you can't turn left/port, tighten the slack from the left line to the rudder). You may also need to loosen the right side a hair to have enough slck get things right.
3. One other note - on the Outfitter the rudder control lever is not centered when properly adjusted and the rudder is straight. I have seen folks adjust the rudder to center the control (OCD?), but this will prevent full rudder movement in one direction. You need to adjust the steering lines for equal movement left and right, regardless of where the control ends up.
The above procedures have always corrected our inability to steer and maintain control in the wind. Sometimes it takes me two tries to get it right.
If you have the bigger sailing rudder (which I recommend for sailing in anything but the lightest winds), the stretching of the various rudder control lines and need for adjustment will be more frequent due to the extra load. We currently have one Outfitter rigged with the bigger rudder and one without.