Be patient. If you can get covers open (like the receiver) open 'em up. Put a fan on it. Sit it in the sun. Twiddle your thumbs.

I'm an R/C sailor - and yeah, once in a while we sink 'em...they'll dry out fine. If it's still weird, try taking apart the rudder servo.....and if it's STILL weird, *ahem* Tell the manufacturer there's something wrong with your radio.....