Sounds like you may have a problem with your rudder control lines. The rudder should work the same either under sail or pedal, so some adjustment may be necessary. Assuming of course that the rudder lines are still intact and not severed--there have been a few problems with the rudder lines being chafed and frayed, and eventually parting where they exit the hull.
So far as additions to make sailing easier (and safer), two Harken blocks, one at the stern, and one amidships will give you a lot quicker and more effective control while under sail. To make the main sheet make more responsive, I attached a Harken 16 mm block to a SS carabiner that I had previously added to the stern handle eye strap. This gave me a clean and fairly friction-free fairlead up to the tag end of the main sheet.
The next thing was to add a West Marine cleat to the upper starboard side just ahead of the midships handle. I then attached a SS shackle to this new cleat. This cleat also comes in handy as an anchor or leash attachment point. I then attached to the shackle a Harken 16 mm block thru which I ran the main sheet (with an overhand knot in the tag end). This tended to cut down the overall friction in the system, and to make the main sheet and sail more responsive while sailing close-hauled.
Hope this helps. Have fun!