a) check that there are no weeds built up on the rudders.

b) check rudder alignment (this can certainly cause difficulty steering)

c) rake mast forward to get the center of effort closer to the balance point of the boat - near the daggerboards.

d) rake rudders forward (this doesn't actually eliminate the helm but it reduces the amount of it you feel by placing the center of lift of the rudders closer to the pivot point).