I wouldn't worry about the width as much as the slot elongating. Sometimes they wear down from the bolt that holds the spring being too tight. Once this happens they are useless; unless of course you find a talented welder that can put bead in there and re-mill them. Even then getting new ones may be the route to go.

Re: the fore and aft play, you may want to consider replacing all the bolts associated to the casting sometimes they get bent and worn; as well, replace the lock bolt on the rudder itself and the springs. And, check you grudgons.

Like Hullflyer said, the Prindle system works great if maintained properly.

If you do get the new rudders get with me off list, I may be interested in your old ones.

Good luck